Vulnerability-Lookup

GHSA-P6VC-4HVX-XVCW

Vulnerability from github – Published: 2026-07-19 18:31 – Updated: 2026-07-20 15:31

Details

In the Linux kernel, the following vulnerability has been resolved:

vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

skb_tunnel_check_pmtu() can change skb->head.

Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.

Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c.

Found by Sashiko.

Severity

9.8 (Critical)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-63993"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-19T16:17:38Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()\n\nskb_tunnel_check_pmtu() can change skb-\u003ehead.\n\nReusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF.\n\nUse instead ip_hdr(skb) as done in drivers/net/bareudp.c\nand drivers/net/geneve.c.\n\nFound by Sashiko.",
  "id": "GHSA-p6vc-4hvx-xvcw",
  "modified": "2026-07-20T15:31:54Z",
  "published": "2026-07-19T18:31:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63993"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5303925e360527243b46a440a04667826bbc72b7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/609e63312c29aad18026a1d3222e123d4b6b0feb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6b8bfce9d2f774d2c2243e0248e03efb99bba6c0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8d435d68d71fb875876b722f4136caf74f2f48bd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9257f56ac47ef1976bcd056cf986a9988eeec67a"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a493efd4336cf19122ae0e4cbb3d31b32d70deea"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dc3bfa050f873371e745bdf478b1f5b738e5733d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-63993 (GCVE-0-2026-63993)

Vulnerability from cvelistv5 – Published: 2026-07-19 14:56 – Updated: 2026-07-20 13:42

Title

vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()

Summary

In the Linux kernel, the following vulnerability has been resolved: vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu() skb_tunnel_check_pmtu() can change skb->head. Reusing old_iph afer skb_tunnel_check_pmtu() can cause an UAF. Use instead ip_hdr(skb) as done in drivers/net/bareudp.c and drivers/net/geneve.c. Found by Sashiko.

Severity

9.8 (Critical)


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

Assigner

Linux

References

8 references

URL	Tags
https://git.kernel.org/stable/c/6b8bfce9d2f774d2c…
https://git.kernel.org/stable/c/9257f56ac47ef1976…
https://git.kernel.org/stable/c/8d435d68d71fb8758…
https://git.kernel.org/stable/c/dc3bfa050f873371e…
https://git.kernel.org/stable/c/609e63312c29aad18…
https://git.kernel.org/stable/c/5303925e360527243…
https://git.kernel.org/stable/c/a493efd4336cf1912…
https://git.kernel.org/stable/c/7d9ef0cb271555d8c…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < 6b8bfce9d2f774d2c2243e0248e03efb99bba6c0 (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < 9257f56ac47ef1976bcd056cf986a9988eeec67a (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < 8d435d68d71fb875876b722f4136caf74f2f48bd (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < dc3bfa050f873371e745bdf478b1f5b738e5733d (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < 609e63312c29aad18026a1d3222e123d4b6b0feb (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < 5303925e360527243b46a440a04667826bbc72b7 (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < a493efd4336cf19122ae0e4cbb3d31b32d70deea (git) Affected: 4cb47a8644cc9eb8ec81190a50e79e6530d0297f , < 7d9ef0cb271555d8cf39fefe6c981e1493b25ecf (git)
Linux	Linux	Affected: 5.9 Unaffected: 0 , < 5.9 (semver) Unaffected: 5.10.259 , ≤ 5.10.* (semver) Unaffected: 5.15.210 , ≤ 5.15.* (semver) Unaffected: 6.1.176 , ≤ 6.1.* (semver) Unaffected: 6.6.143 , ≤ 6.6.* (semver) Unaffected: 6.12.93 , ≤ 6.12.* (semver) Unaffected: 6.18.35 , ≤ 6.18.* (semver) Unaffected: 7.0.12 , ≤ 7.0.* (semver) Unaffected: 7.1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/vxlan/vxlan_core.c"
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          "vendor": "Linux",
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              "version": "5.9"
            },
            {
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "status": "unaffected",
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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      "descriptions": [
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          "url": "https://git.kernel.org/stable/c/7d9ef0cb271555d8cf39fefe6c981e1493b25ecf"
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      ],
      "title": "vxlan: do not reuse cached ip_hdr() value after skb_tunnel_check_pmtu()",
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    "state": "PUBLISHED"
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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.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-P6VC-4HVX-XVCW

CVE-2026-63993 (GCVE-0-2026-63993)

Tags

Sightings

Nomenclature