CVE-2026-31657

Unspecified impact via unpinned gateway reference

Published Apr 24, 2026 · Updated Apr 24, 2026

Use-after-free in Linux Kernel batman-adv allows attackers to cause unspecified impact through concurrent gateway claim operations. The batadv_bla_add_claim() path can replace claim->backbone_gw and release its last reference while the netlink dump and batadv_bla_check_claim() readers dereference the stale pointer without first pinning the gateway. Reachability requires bridge-loop-avoidance claim activity and a race between gateway replacement and a reader; published assessments disagree on whether access is remote or local, and no demonstrated consequence is defined.

CVSS severity9.8
Critical
EPSS probability0.40%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel batman-adv allows attackers to cause unspecified impact through concurrent gateway claim operations. The batadv_bla_add_claim() path can replace claim->backbone_gw and release its last reference while the netlink dump and batadv_bla_check_claim() readers dereference the stale pointer without first pinning the gateway. Reachability requires bridge-loop-avoidance claim activity and a race between gateway replacement and a reader; published assessments disagree on whether access is remote or local, and no demonstrated consequence is defined.

The record

CVE
CVE-2026-31657
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-476
Attack vector
Unavailable
Privileges
Unavailable

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=23721387c409087fd3b97e274f34d3ddc0970b74 <1f2dc36c297d27733f1b380ea644cf15a361bd7b
  2. Affected versionversion=23721387c409087fd3b97e274f34d3ddc0970b74 <2f55b58b5a0bbed192d60c444a45a49cdf1b545f
  3. Affected versionversion=23721387c409087fd3b97e274f34d3ddc0970b74 <4dee4c0688443aaf5bbec74aa203c851d1d53c35
  4. Affected versionversion=23721387c409087fd3b97e274f34d3ddc0970b74 <7962b522222628596ca9ecc8722efc95367aadbd
  5. Affected versionversion=23721387c409087fd3b97e274f34d3ddc0970b74 <82d8701b2c930d0e96b0dbc9115a218d791cb0d2
  6. Affected versionversion=23721387c409087fd3b97e274f34d3ddc0970b74 <f4858832ddef2f39f21e30b7226bbcd3c4b2bc96
  7. Affected versionversion=3.5

What conditions does exploitation require?

Attack vectorUnavailable in this record.
Required privilegesUnavailable in this record.

What is affected?

The Linux Kernel Organization · Linux Kernelversion=23721387c409087fd3b97e274f34d3ddc0970b74 <1f2dc36c297d27733f1b380ea644cf15a361bd7b; version=23721387c409087fd3b97e274f34d3ddc0970b74 <2f55b58b5a0bbed192d60c444a45a49cdf1b545f; version=23721387c409087fd3b97e274f34d3ddc0970b74 <4dee4c0688443aaf5bbec74aa203c851d1d53c35; version=23721387c409087fd3b97e274f34d3ddc0970b74 <7962b522222628596ca9ecc8722efc95367aadbd; version=23721387c409087fd3b97e274f34d3ddc0970b74 <82d8701b2c930d0e96b0dbc9115a218d791cb0d2; version=23721387c409087fd3b97e274f34d3ddc0970b74 <f4858832ddef2f39f21e30b7226bbcd3c4b2bc96; version=3.5

Published CVSS scores

9.8Linux kernel CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8Oracle LinuxCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
VectorUnavailable
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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