CVE-2026-23247 json
tcp: secure_seq: add back ports to TS offset
published 2026-03-18 7 mo ago modified 2026-11-05 3 d ago also EUVD-2026-12810
- cvss
- 5.5
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 6%
- public exploits
- 0
- none known
Summary
In the Linux kernel, the following vulnerability has been resolved:
tcp: secure_seq: add back ports to TS offset
This reverts 28ee1b746f49 ("secure_seq: downgrade to per-host timestamp offsets")
tcp_tw_recycle went away in 2017.
Zhouyan Deng reported off-path TCP source port leakage via SYN cookie side-channel that can be fixed in multiple ways.
One of them is to bring back TCP ports in TS offset randomization.
As a bonus, we perform a single siphash() computation to provide both an ISN and a TS offset.
Patch / fix
- Linux Linux 4.11, 6.1.191, 6.6.160, 6.12.94, 6.18.17, 6.19.7, 7.0
- linux Debian 13 6.12.94-1
- linux Debian 14 6.19.8-1
debian advisories DEBIAN-CVE-2026-23247
- git.kernel.org/stable/c/025f532d8c5cfac77845e50daab7f478b360f2ac commit
- git.kernel.org/stable/c/e873e8c16b2fb743a381a9e59c108e63512301ec commit
- git.kernel.org/stable/c/5da5662181ef8a251e3ba564903002c2e87de452 commit
- git.kernel.org/stable/c/eae2f14ab2efccdb7480fae7d42c4b0116ef8805 commit
- git.kernel.org/stable/c/46e5b0d7cf55821527adea471ffe52a5afbd9caf commit
- git.kernel.org/stable/c/165573e41f2f66ef98940cf65f838b2cb575d9d1 commit
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-23247 updated cvss 5.3
kernel: Linux kernel: Information disclosure via off-path TCP source port leakage
-
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 moreaffected: no fix planned “Out of support scope”
-
Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 moreaffected: no fix available “Fix deferred”
-
Red Hat Enterprise Linux 10 kernelaffected: no fix available
-
Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 morenot affected: vulnerable code not present
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 3 d ago
Exploit prediction
0.17% chance of exploitation in the next 30 days, higher than 6% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Affected products
- Linux Linux
Classification
- Technology feeds
References
- git.kernel.org /stable/c/025f532d8c5cfac77845e50daab7f478b360f2ac
- git.kernel.org /stable/c/e873e8c16b2fb743a381a9e59c108e63512301ec
- git.kernel.org /stable/c/5da5662181ef8a251e3ba564903002c2e87de452
-
git.kernel.org
/stable/c/eae2f14ab2efccdb7480fae7d42c4b0116ef8805
patch
-
git.kernel.org
/stable/c/46e5b0d7cf55821527adea471ffe52a5afbd9caf
patch
-
git.kernel.org
/stable/c/165573e41f2f66ef98940cf65f838b2cb575d9d1
patch
Sources
- CVE List CVE-2026-23247
- NVD CVE-2026-23247
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.