Vulnerability-Lookup

GHSA-WJHP-5P5W-QMHH

Vulnerability from github – Published: 2026-05-01 15:30 – Updated: 2026-05-08 21:31

Details

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

net: use skb_header_pointer() for TCPv4 GSO frag_off check

Syzbot reported a KMSAN uninit-value warning in gso_features_check() called from netif_skb_features() [1].

gso_features_check() reads iph->frag_off to decide whether to clear mangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr() can rely on skb header offsets that are not always safe for direct dereference on packets injected from PF_PACKET paths.

Use skb_header_pointer() for the TCPv4 frag_off check so the header read is robust whether data is already linear or needs copying.

[1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407

Severity ?

5.5 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2026-43036"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-908"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-01T15:16:48Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: use skb_header_pointer() for TCPv4 GSO frag_off check\n\nSyzbot reported a KMSAN uninit-value warning in gso_features_check()\ncalled from netif_skb_features() [1].\n\ngso_features_check() reads iph-\u003efrag_off to decide whether to clear\nmangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr()\ncan rely on skb header offsets that are not always safe for direct\ndereference on packets injected from PF_PACKET paths.\n\nUse skb_header_pointer() for the TCPv4 frag_off check so the header read\nis robust whether data is already linear or needs copying.\n\n[1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407",
  "id": "GHSA-wjhp-5p5w-qmhh",
  "modified": "2026-05-08T21:31:20Z",
  "published": "2026-05-01T15:30:37Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-43036"
    },
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      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/cc91202fc20a44aab4c206f12a2bfe05da936051"
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      "url": "https://git.kernel.org/stable/c/d970341cfa5594614c7a6634886c7688b4f5cafd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f7a6cd508e9e825a2c69fa9e13d41ee156852f25"
    }
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  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-43036 (GCVE-0-2026-43036)

Vulnerability from cvelistv5 – Published: 2026-05-01 14:15 – Updated: 2026-05-11 22:16

Title

net: use skb_header_pointer() for TCPv4 GSO frag_off check

Summary

In the Linux kernel, the following vulnerability has been resolved: net: use skb_header_pointer() for TCPv4 GSO frag_off check Syzbot reported a KMSAN uninit-value warning in gso_features_check() called from netif_skb_features() [1]. gso_features_check() reads iph->frag_off to decide whether to clear mangleid_features. Accessing the IPv4 header via ip_hdr()/inner_ip_hdr() can rely on skb header offsets that are not always safe for direct dereference on packets injected from PF_PACKET paths. Use skb_header_pointer() for the TCPv4 frag_off check so the header read is robust whether data is already linear or needs copying. [1] https://syzkaller.appspot.com/bug?extid=1543a7d954d9c6d00407

Severity ?

No CVSS data available.

Assigner

Linux

References

4 references

URL	Tags
https://git.kernel.org/stable/c/f7a6cd508e9e825a2…
https://git.kernel.org/stable/c/cc91202fc20a44aab…
https://git.kernel.org/stable/c/d970341cfa5594614…
https://git.kernel.org/stable/c/ddc748a391dd8642b…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: cbc53e08a793b073e79f42ca33f1f3568703540d , < f7a6cd508e9e825a2c69fa9e13d41ee156852f25 (git) Affected: cbc53e08a793b073e79f42ca33f1f3568703540d , < cc91202fc20a44aab4c206f12a2bfe05da936051 (git) Affected: cbc53e08a793b073e79f42ca33f1f3568703540d , < d970341cfa5594614c7a6634886c7688b4f5cafd (git) Affected: cbc53e08a793b073e79f42ca33f1f3568703540d , < ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0 (git)
Linux	Linux	Affected: 4.7 Unaffected: 0 , < 4.7 (semver) Unaffected: 6.12.81 , ≤ 6.12.* (semver) Unaffected: 6.18.22 , ≤ 6.18.* (semver) Unaffected: 6.19.12 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix)

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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-WJHP-5P5W-QMHH

CVE-2026-43036 (GCVE-0-2026-43036)

Tags

Sightings

Nomenclature