CVE-2026-80847
tcp: clamp route advmss to TCP_MIN_MSS
No known exploitation. EPSS puts it in the 10th percentile. No fix published yet.
What to do
No fixed build or workaround is published yet. Limit exposure and watch for a patch.
What it is
From the CVE record
In the Linux kernel, the following vulnerability has been resolved: tcp: clamp route advmss to TCP_MIN_MSS tcp_select_initial_window() assumes that callers never pass an MSS smaller than 1, but route-derived advmss values can violate that assumption. A too-small explicit RTAX_ADVMSS is one way to get there, but it is not the only one. The same divide-by-zero can also be reached through the "default advmss" path when RTAX_ADVMSS is left at 0 and the effective advmss is later driven down by route MTU and min_adv_mss. Introduce a tcp_dst_advmss() helper that clamps route advmss to TCP_MIN_MSS before TCP consumes it, and use it in the TCP paths that derive advmss from dst metrics. This keeps the effective MSS from dropping to zero before tcp_select_initial_window() rounds the receive window.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.2% chance of exploitation activity in the next 30 days, which ranks it in the 10th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
5 events over 17 days, from the signal feeds we watch.
- Record updated
- OpenVAS check added
- Record updated
- Publishedrecord updated
Affected products
Sources
References in the record
- git.kernel.org/stable/c/eaf4af9bd6975c2eff8d48820937c83032d968dc
- git.kernel.org/stable/c/cfb44c6028e6f979720315e0772bbd0d4d33ed61
- git.kernel.org/stable/c/6b8c20bf61924dfc38fefb145c9f7406d73fae53
And 2 more references. See all after sign-in
In the news
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