VulnerabilityPublished 1 May 2026Updated 21 Oct 2026

CVE-2026-43036: Linux kernel · net: use skb_header_pointer() for TCPv4 GSO frag_off check

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f7a6cd508e9e825a2c69fa9e13d41ee156852f25 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:18 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f7a6cd508e9e825a2c69fa9e13d41ee156852f25, ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0, d970341cfa5594614c7a6634886c7688b4f5cafd +2

Exploitation evidence

Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ cbc53e08a793b073e79f42ca33f1f3568703540d, < f7a6cd508e9e825a2c69fa9e13d41ee156852f25	Fixed in f7a6cd508e9e825a2c69fa9e13d41ee156852f25
LinuxLinux	Affected ≥ cbc53e08a793b073e79f42ca33f1f3568703540d, < ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0	Fixed in ddc748a391dd8642ba6b2e4fe22e7f2ddf84b7f0
LinuxLinux	Affected ≥ cbc53e08a793b073e79f42ca33f1f3568703540d, < d970341cfa5594614c7a6634886c7688b4f5cafd	Fixed in d970341cfa5594614c7a6634886c7688b4f5cafd
LinuxLinux	Affected ≥ cbc53e08a793b073e79f42ca33f1f3568703540d, < cc91202fc20a44aab4c206f12a2bfe05da936051	Fixed in cc91202fc20a44aab4c206f12a2bfe05da936051
LinuxLinux	Affected ≥ cbc53e08a793b073e79f42ca33f1f3568703540d, < 5057502630fbc8ce468ff617ff59af275960b537	Fixed in 5057502630fbc8ce468ff617ff59af275960b537
LinuxLinux	Affected =4.7	Fixed in–

Description

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

References

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