In the Linux kernel, the following vulnerability has been resolved: tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF…
CVE-2026-72502 · published 15 Aug 2026
How serious is it
- Severity: high, CVSS score 7.5 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-72502?
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Who is affected
- Linux Linux: 4.8
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
tcp: ipv6: clamp default adverting MSS to avoid GSO_BY_FRAGS (0xFFFF)
When MTU is large, ip6_default_advmss() can return IPV6_MAXPLEN (65535).
This is interpreted by TCP as mss_clamp, allowing the MSS to reach 65535.
However, 0xFFFF is also used as a magic value GSO_BY_FRAGS in the kernel.
If a TCP packet with gso_size=0xFFFF is passed to skb_segment(), it will
be mistakenly treated as GSO_BY_FRAGS, leading to a NULL pointer
dereference because local TCP packets do not use frag_list.
Fix this by returning min(IPV6_MAXPLEN, GSO_BY_FRAGS - 1) (65534) from
ip6_default_advmss() when MTU is large.
Also update the stale comment in ip6_default_advmss() which suggested
that IPV6_MAXPLEN is returned to mean "any MSS".
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/21f69ac1879bb970588d5e7c12a96e6542f7c1a7
- git.kernel.org/stable/c/2bf43d0e2e6a27d52a7d624e2d6b9116972e8a22
- git.kernel.org/stable/c/560b33b434e922ef97f9ff23aa2e909ef7aacd5c
- git.kernel.org/stable/c/572fff10819dfc359298d1f774839e76a4d96f93
- git.kernel.org/stable/c/8e6214a530c03e341dc1b0a846c8f2b716b3551a
- git.kernel.org/stable/c/a210791f33345aa87187f7d7a9f3b9b7f4a28e6d
- git.kernel.org/stable/c/c0db3dc2ac323b6c4b76adede3b355a9daa6dea8
- git.kernel.org/stable/c/d774cdbda6634a78d0f2baf201ee5a8c57f3bc0e
Merged from NVD. Last updated 23 Oct 2026. All vulnerabilities · RSS · JSON