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🛡️ CVE-2026-31680 — kernel

🟠 CVSS 7.8 — High ✅ No Known Exploit NVD
7.8
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

net: ipv6: flowlabel: defer exclusive option free until RCU teardown

In the Linux kernel, the following vulnerability has been resolved:

net: ipv6: flowlabel: defer exclusive option free until RCU teardown

ip6fl_seq_show() walks the global flowlabel hash under the seq-file

RCU read-side lock and prints fl->opt->opt_nflen when an option block

is present.

Exclusive flowlabels currently free fl->opt as soon as fl->users

drops to zero in fl_release(). However, the surrounding

struct ip6_flowlabel remains visible in the global hash table until

later garbage collection removes it and fl_free_rcu() finally tears it

down.

A concurrent /proc/net/ip6_flowlabel reader can therefore race that

early kfree() and dereference freed option state, triggering a crash

in ip6fl_seq_show().

Fix this by keeping fl->opt alive until fl_free_rcu(). That matches

the lifetime already required for the enclosing flowlabel while readers

can still reach it under RCU.

How this vulnerability can be exploited

This issue can be reached with local access to the system, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity high, availability high.

Affected software

CVE-2026-31680 is recorded against 2 packages.

  • kernel (from 6.19.0 up to 6.19.12)
  • linux-kernel

Timeline and source

Published on 25 April 2026 and last revised on 12 August 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

cert-portal.siemens.com (Web)
cert-portal.siemens.com (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
git.kernel.org (Web)
github.com (Advisory)
nvd.nist.gov (Advisory)
git.kernel.org (Package)

CVE-2026-31680 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity High
CVSS Score 7.8
CVSS Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE N/A
Public Exploit ✅ No
Source NVD
Published 2026-04-25
Updated 2026-08-20
Modified 2026-08-12

Affected Packages

Software From version Fixed in
kernel 6.19.0 6.19.12
linux-kernel — —

References

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.