Vulnerability-Lookup

GHSA-5P85-47CF-3663

Vulnerability from github – Published: 2026-09-29 18:31 – Updated: 2026-09-30 21:31

Details

Impact summary: A remote attacker able to spoof packets to a server using the OpenSSL QUIC implementation might use the server for an amplification of a DDoS attack.

CWE: CWE-440: Expected Behavior Violation

Description: OpenSSL's QUIC stack, when operating as a server, enforces client address validation (RFC 9000, Section 8), to confirm the peer address is not used for a traffic amplification attack. If this feature is disabled on the server, the QUIC stack limits the amount of server data that can be sent to 3 times the amount of data received from the peer address, until such time as the TLS handshake is completed.

The OpenSSL QUIC server, when operating in non-validation mode, adds the length of the whole datagram received to the unvalidated credit limit when processing each QUIC packet in the datagram. A remote peer may, after establishing a connection with an initial client hello frame, send a subsequent datagram containing multiple QUIC packets, leading the server to account the entire datagram length for each packet in the datagram, resulting in the server believing that the peer has sent more data than it actually has, thereby violating the 3x amplification limit mandated by the RFC.

FIPS impact: no As the QUIC stack lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.

Severity

3.7 (Low)


                  
                    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

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{
  "affected": [],
  "aliases": [
    "CVE-2026-35191"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-440"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-29T16:17:07Z",
    "severity": "LOW"
  },
  "details": "Issue summary: The OpenSSL QUIC server, when configured to not preform address\nvalidation, can be forced to count incoming packets multiple times in its\nunvalidated credit computation, leading to a violation of the RFC 9000\nunvalidated connection amplification limit of 3 times the amount of data\nreceived.\n\nImpact summary: A remote attacker able to spoof packets to a server using the\nOpenSSL QUIC implementation might use the server for an amplification of\na DDoS attack.\n\nCWE: CWE-440: Expected Behavior Violation \n\nDescription: OpenSSL\u0027s QUIC stack, when operating as a server, enforces client\naddress validation (RFC 9000, Section 8), to confirm the peer address is not\nused for a traffic amplification attack.  If this feature is disabled on the\nserver, the QUIC stack limits the amount of server data that can be sent to 3\ntimes the amount of data received from the peer address, until such time as the\nTLS handshake is completed.\n\nThe OpenSSL QUIC server, when operating in non-validation mode, adds the\nlength of the whole datagram received to the unvalidated credit limit when\nprocessing each QUIC packet in the datagram. A remote peer may,\nafter establishing a connection with an initial client hello frame, send a\nsubsequent datagram containing multiple QUIC packets, leading the server to\naccount the entire datagram length for each packet in the datagram, resulting\nin the server believing that the peer has sent more data than it actually has,\nthereby violating the 3x amplification limit mandated by the RFC.\n\nFIPS impact: no\nAs the QUIC stack lives outside the FIPS module boundary, no FIPS modules\nare affected by this CVE.",
  "id": "GHSA-5p85-47cf-3663",
  "modified": "2026-09-30T21:31:58Z",
  "published": "2026-09-29T18:31:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-35191"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/0fe4442d4f8ea3af8a174046dae176e0d4717239"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/2de4c35fb13fc58f43fd8dc1d261700472ce72e5"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/e44292e58b090014232ef75bd400393851b24d1a"
    },
    {
      "type": "WEB",
      "url": "https://openssl-library.org/news/secadv/20260929.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-35191 (GCVE-0-2026-35191)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:32 – Updated: 2026-09-30 20:11

Title

QUIC Unvalidated Amplification Credit may be Over Accounted

Summary

Issue summary: The OpenSSL QUIC server, when configured to not preform address validation, can be forced to count incoming packets multiple times in its unvalidated credit computation, leading to a violation of the RFC 9000 unvalidated connection amplification limit of 3 times the amount of data received. Impact summary: A remote attacker able to spoof packets to a server using the OpenSSL QUIC implementation might use the server for an amplification of a DDoS attack. CWE: CWE-440: Expected Behavior Violation Description: OpenSSL's QUIC stack, when operating as a server, enforces client address validation (RFC 9000, Section 8), to confirm the peer address is not used for a traffic amplification attack. If this feature is disabled on the server, the QUIC stack limits the amount of server data that can be sent to 3 times the amount of data received from the peer address, until such time as the TLS handshake is completed. The OpenSSL QUIC server, when operating in non-validation mode, adds the length of the whole datagram received to the unvalidated credit limit when processing each QUIC packet in the datagram. A remote peer may, after establishing a connection with an initial client hello frame, send a subsequent datagram containing multiple QUIC packets, leading the server to account the entire datagram length for each packet in the datagram, resulting in the server believing that the peer has sent more data than it actually has, thereby violating the 3x amplification limit mandated by the RFC. FIPS impact: no As the QUIC stack lives outside the FIPS module boundary, no FIPS modules are affected by this CVE.

Severity

3.7 (Low)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-30 19:35 UTC

CWE

CWE-440 - Expected Behavior Violation

Assigner

openssl CNA under the mitre root

CNA scorecard B 78/100 over 48 records in the last 180 days details

References

4 references

URL	Tags
https://openssl-library.org/news/secadv/20260929.txt	vendor-advisory
https://github.com/openssl/openssl/commit/e44292e…	patch
https://github.com/openssl/openssl/commit/2de4c35…	patch
https://github.com/openssl/openssl/commit/0fe4442…	patch

Impacted products

1 product

Vendor	Product	Version
OpenSSL	OpenSSL	Affected: 4.0.0 , < 4.0.3 (semver) Affected: 3.6.0 , < 3.6.5 (semver) Affected: 3.5.0 , < 3.5.9 (semver)

Date Public

2026-09-29 14:21

Credits

Ali Firas Nikolas Gauder (NVIDIA) Neil Horman

Show details on NVD website

JSON

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              "attackVector": "NETWORK",
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              "baseSeverity": "LOW",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "NONE",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L",
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                "id": "CVE-2026-35191",
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          "shortName": "CISA-ADP"
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    ],
    "cna": {
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          "vendor": "OpenSSL",
          "versions": [
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              "status": "affected",
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        {
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            "content": {
              "text": "Low"
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        }
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      "source": {
        "discovery": "UNKNOWN"
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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

Sightings and recorded dates, grouped by day · UTC

Order JSON

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.

Publication & reservation Sightings KEV catalogs Other timestamps

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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.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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