Unknown

CVE-2026-90054 — tcp: fix corruption of urgent data on multi-segment retransmit

In the Linux kernel, the following vulnerability has been resolved: tcp: fix corruption of urgent data on multi-segment retransmit On the normal xmit path, while in urgent mode we refuse to build a multi-segment TSO packet, so every segment gets its own urg_ptr: /* tcp_write_xmit() */ limit = mss_now; if (tso_segs > 1 && !tcp_urg_mode(tp)) limit = tcp_mss_split_point(...); The retransmit path has no such guard. __tcp_retransmit_skb() builds a segs > 1 skb and hands it to the GSO layer, which only advances th->seq per segment and copies urg_ptr verbatim: /* __tcp_retransmit_skb() */ len = cur_mss * segs; /* segs > 1, no urg_mode check */ ... /* tcp_gso_segment(): bumps seq only, urg_ptr is copied */ urg_ptr is an offset from the segment's own seq, so a copied value points at a different place on each segment. The receiver rebuilds the absolute urgent seq as seg.seq + urg_ptr, so it walks a moving urgent point instead of the one OOB byte: seg1 seq 1 urg_ptr 5001 -> urgent @ 5001 (ok) seg2 seq 1001 urg_ptr 5001 -> urgent @ 6001 (wrong, +MSS) seg3 seq 2001 urg_ptr 5001 -> urgent @ 7001 (wrong, +2*MSS) The real OOB byte is never pointed at, so the receiver stops splicing it out and delivers it as normal in-band data, corrupting the stream. Guard the retransmit length like the xmit path: keep segs = 1 while in urgent mode.

Published Sep 17, 2026 · Updated Oct 19, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.22%

ahead of 11% of scored CVEs · Oct 19, 2026

Affects

Linux

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < 8eb51013b6308870479a64b4a2a018697b997849≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < 711bfd762bec05fb19bc3b17cbb157c39f4e66da≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < 3d4e005c198dc410ad568f832bffa7569c059ff8≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < 4fd2ee4ac154c204d95d8db72221446dac5af9b8≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < ebe55406404f3cb28e36d2b668e2c6c05026ec29≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < b8f08a94b2a4addc39249dcf9c792e786108621b≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < 47eb90299e6882d6445672530dd7c51ac33ebdbd≥ 10d3be569243def8d92ac3722395ef5a59c504e6 and < ce2b807f42ed5e55567b8864ab72963f90779270 and 1 more version 4.7	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 19, 2026 · 4 reading(s) · max 0.22%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Sep 17, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× References added · Oct 19, 2026 – Oct 19, 2026
1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

10 on the record

git.kernel.org/stable/c/711bfd762bec05fb19bc3b17cbb157c39f4e66da
NIST National Vulnerability Database
git.kernel.org/stable/c/b8f08a94b2a4addc39249dcf9c792e786108621b
NIST National Vulnerability Database
git.kernel.org/stable/c/8eb51013b6308870479a64b4a2a018697b997849
NIST National Vulnerability Database
git.kernel.org/stable/c/4fd2ee4ac154c204d95d8db72221446dac5af9b8
NIST National Vulnerability Database
git.kernel.org/stable/c/3d4e005c198dc410ad568f832bffa7569c059ff8
NIST National Vulnerability Database
git.kernel.org/stable/c/ce2b807f42ed5e55567b8864ab72963f90779270
NIST National Vulnerability Database
git.kernel.org/stable/c/ebe55406404f3cb28e36d2b668e2c6c05026ec29
NIST National Vulnerability Database
github.com/advisories/GHSA-cwq3-366f-g758
GitHub Security Advisories
git.kernel.org/stable/c/47eb90299e6882d6445672530dd7c51ac33ebdbd
NIST National Vulnerability Database
nvd.nist.gov/vuln/detail/CVE-2026-90054
GitHub Security Advisories

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Unknown CVE-2026-98866 sched/cache: Introduce task_struct->sched_cache_grp to fix UAF 1d
Unknown CVE-2026-98867 dm-pcache: bound the logical key offset from persistent memory 1d
Unknown CVE-2026-98868 dm-pcache: reject a kset that overruns its segment 1d
Unknown CVE-2026-98856 kprobes: Skip disarmed probes when checking optkprobe overlap 1d
Unknown CVE-2026-98857 ipvs: bound LBLCR and LBLC cache growth 1d
Unknown CVE-2026-98858 io_uring: fix task_work add use-after-free with SQPOLL 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-90054 is "tcp: fix corruption of urgent data on multi-segment retransmit", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.22% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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