CVE-2026-93203

batman-adv: bla: avoid CRC corruption due to parallel claim add

Published Sep 17, 2026 CVSS 3.1 · 7.1 High EPSS < 1% KEV · Not listed

Description

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

batman-adv: bla: avoid CRC corruption due to parallel claim add

batadv_bla_add_claim() is used to add claims and modify the backbone of
claims for CLAIM frames from remote backbones and local packets. When it
handles a claim, it needs to either

* add the new claim's CRC to the backbone CRC
* remove the already existing claim's CRC from the old backbone and add it
to the new backbone

But when the "new" claim code was running in parallel to the "change
backbone" code, it can happen that the CRC was invalid because the
backbone_gw of the claim was changed twice in the "new" claim code path:

* CPU0 creates the claim for gateway A and publishes it in the claim
hash. The crc16 of the address has not yet been added to A's crc at
this point.

* CPU1 processes a claim frame of gateway B for the same client, finds
the just published claim, and performs the ownership change: it
switches the pointer to B, removes the crc16 from A's crc - which
never contained it - and adds it to B's crc.

* CPU0 continues behind the creation branch, unconditionally switches
the pointer back to A without compensating B's crc (its remove_crc
is false for the creation path), and finally adds the crc16 to A's
crc

The CRC is then wrong for both:

* claim belongs to A: but CRC is not part of backbone A's CRC
* claim doesn't belong to B: CRC is still part of backbone B's CRC

This wrong CRC is never recomputated from the stored claims. For local
backbone claims, this can also not recovered using syncs.

To avoid this, split the functionality in clear separate parts:

* new claim which always adds claim CRC to the backbone CRC (but never
changes the already set backbone_gw of the claim back)

* update of existing claim which automatically changes the backbone_gw
entry and only updates both backbone CRCs when there was an actual change

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< 3d4a9ae2c69c0fe4c3c69587288241243bb7a39b
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< ad982d925f00d860d2467811256ffadcccd9e4a7
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< d5b0e7574da5a485f4dbec32a15911900a4487c2
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< a3e07db74f22a85aeeb51c600da5c98b9cbca11f
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< 1d390db003cbb52cdd86837608bff3794501a5ea
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< 8bcfa58c4277bff1882a23547c37ab08aa1de12f
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< e54602d9e38db8573f2097d60c7ea8be0a5af1fa
`23721387c409087fd3b97e274f34d3ddc0970b74`	affected	< 08645ab95768b88e2ff85a89211994651710465b

Linux

affected

Version	Status	Constraints
`3.5`	affected	—
`0`	unaffected	< 3.5
`5.10.270`	unaffected	≤ 5.10.*
`5.15.221`	unaffected	≤ 5.15.*
`6.1.188`	unaffected	≤ 6.1.*
`6.6.157`	unaffected	≤ 6.6.*
`6.12.110`	unaffected	≤ 6.12.*
`6.18.52`	unaffected	≤ 6.18.*
`7.2.6`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[23721387c409087fd3b97e274f34d3ddc0970b74,3d4a9ae2c69c0fe4c3c69587288241243bb7a39b)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,ad982d925f00d860d2467811256ffadcccd9e4a7)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,d5b0e7574da5a485f4dbec32a15911900a4487c2)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,a3e07db74f22a85aeeb51c600da5c98b9cbca11f)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,1d390db003cbb52cdd86837608bff3794501a5ea)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,8bcfa58c4277bff1882a23547c37ab08aa1de12f)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,e54602d9e38db8573f2097d60c7ea8be0a5af1fa)`	affected	code_commit	—
`[23721387c409087fd3b97e274f34d3ddc0970b74,08645ab95768b88e2ff85a89211994651710465b)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`3.5`	affected	generic	—
`[0,3.5)`	unaffected	generic	—
`[5.10.270,5.11.0)`	unaffected	semver	—
`[5.15.221,5.16.0)`	unaffected	semver	—
`[6.1.188,6.2.0)`	unaffected	semver	—
`[6.6.157,6.7.0)`	unaffected	semver	—
`[6.12.110,6.13.0)`	unaffected	semver	—
`[6.18.52,6.19.0)`	unaffected	semver	—
`[7.2.6,7.3.0)`	unaffected	semver	—
`[7.3-rc1,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4817-1	linux-6.12 security update
Debian DLA	DLA-4841-1	linux security update
Debian DSA	DSA-6528-1	linux security update
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Adjacent Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact Low

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.336% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/08645ab95768b88e2ff85a89211994651710465b
https://git.kernel.org/stable/c/1d390db003cbb52cdd86837608bff3794501a5ea
https://git.kernel.org/stable/c/3d4a9ae2c69c0fe4c3c69587288241243bb7a39b
https://git.kernel.org/stable/c/8bcfa58c4277bff1882a23547c37ab08aa1de12f
https://git.kernel.org/stable/c/a3e07db74f22a85aeeb51c600da5c98b9cbca11f
https://git.kernel.org/stable/c/ad982d925f00d860d2467811256ffadcccd9e4a7
https://git.kernel.org/stable/c/d5b0e7574da5a485f4dbec32a15911900a4487c2
https://git.kernel.org/stable/c/e54602d9e38db8573f2097d60c7ea8be0a5af1fa

History

Sep 19, 2026 10:00 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-362

Sep 19, 2026 6:30 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses	CWE-362

Sep 19, 2026 9:00 AM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-362

Sep 18, 2026 9:30 PM Scoring metrics updated View changes

Type	Values Removed	Values Added
Metrics		cvssV3_1 `{'score': 7.1, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H'}`

Sep 17, 2026 4:30 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: batman-adv: bla: avoid CRC corruption due to parallel claim add batadv_bla_add_claim() is used to add claims and modify the backbone of claims for CLAIM frames from remote backbones and local packets. When it handles a claim, it needs to either * add the new claim's CRC to the backbone CRC * remove the already existing claim's CRC from the old backbone and add it to the new backbone But when the "new" claim code was running in parallel to the "change backbone" code, it can happen that the CRC was invalid because the backbone_gw of the claim was changed twice in the "new" claim code path: * CPU0 creates the claim for gateway A and publishes it in the claim hash. The crc16 of the address has not yet been added to A's crc at this point. * CPU1 processes a claim frame of gateway B for the same client, finds the just published claim, and performs the ownership change: it switches the pointer to B, removes the crc16 from A's crc - which never contained it - and adds it to B's crc. * CPU0 continues behind the creation branch, unconditionally switches the pointer back to A without compensating B's crc (its remove_crc is false for the creation path), and finally adds the crc16 to A's crc The CRC is then wrong for both: * claim belongs to A: but CRC is not part of backbone A's CRC * claim doesn't belong to B: CRC is still part of backbone B's CRC This wrong CRC is never recomputated from the stored claims. For local backbone claims, this can also not recovered using syncs. To avoid this, split the functionality in clear separate parts: * new claim which always adds claim CRC to the backbone CRC (but never changes the already set backbone_gw of the claim back) * update of existing claim which automatically changes the backbone_gw entry and only updates both backbone CRCs when there was an actual change
Title		batman-adv: bla: avoid CRC corruption due to parallel claim add
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/08645ab95768b88e2ff85a89211994651710465b https://git.kernel.org/stable/c/1d390db003cbb52cdd86837608bff3794501a5ea https://git.kernel.org/stable/c/3d4a9ae2c69c0fe4c3c69587288241243bb7a39b https://git.kernel.org/stable/c/8bcfa58c4277bff1882a23547c37ab08aa1de12f https://git.kernel.org/stable/c/a3e07db74f22a85aeeb51c600da5c98b9cbca11f https://git.kernel.org/stable/c/ad982d925f00d860d2467811256ffadcccd9e4a7 https://git.kernel.org/stable/c/d5b0e7574da5a485f4dbec32a15911900a4487c2 https://git.kernel.org/stable/c/e54602d9e38db8573f2097d60c7ea8be0a5af1fa