The vulnerability in batman-adv's receive path is a textbook stale pointer bug: pskb_may_pull() can reallocate the skb's backing memory, invalidating any cached header pointers, yet the ethernet header pointer was not refreshed after this call while the VLAN header pointer was. When TT (translation table) and AP isolation logic dereferences this stale pointer, it triggers a use-after-free. The developers demonstrably understood the requirement—the VLAN header pointer is correctly reassigned in the same function—but the ethernet path was missed, likely because the developer was focused on the VLAN change and applied the fix locally without auditing unrelated header pointers in the same block. This 'local coherence without global coverage' failure mode is the operative risk. The fix is trivial (reassign ethhdr after pskb_may_pull()), but the structural question is whether batman-adv has other code paths with the same pattern: pskb_may_pull() followed by multiple skb header pointer dereferences where only some pointers were refreshed. Audit functions in the TX path, fragmentation handling, and multi-interface scenarios for this exact pattern. The deeper concern is that TT and AP isolation logic—which makes routing decisions affecting mesh topology—depends on this pointer, meaning the blast radius of a stale dereference extends beyond local crash to potential table state corruption propagating through the mesh protocol. For prioritization: treat any batman-adv code touching pskb_may_pull() with multiple header pointer accesses as high-risk until audited.
CVE-2026-72235
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: batman-adv: retrieve ethhdr after potential skb realloc on RX pskb_may_pull() in batadv_interface_rx() could reallocate the buffer behind the skb. Variables which were pointing to the old buffer need to be reassigned to avoid an use-after-free. This was done correctly for the VLAN header but missed for the ethernet header which is later used for the TT and AP isolation handling.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysisA detailed technical summary for this CVE is being prepared.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Adjacent
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataThere is no version to upgrade to and no patch to apply. Every affected install stays exposed until the vendor ships a fix — or somebody else builds one.
Free. We build fixes in the order the community asks for them — and we’ll tell you the moment this one lands.
We develop and verify an original fix where the vendor hasn’t, from $4,900. Deployed to your staging first — never straight to production.
Scope it with usSee what else the community needs solved on the solutions-needed board.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-72235 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesThe vulnerability in batman-adv's receive path is a textbook stale pointer bug: `pskb_may_pull()` can reallocate the skb's backing memory, invalidating any cached header pointers, yet the ethernet header pointer was not refreshed after this call while the VLAN header pointer was. When TT (translation table) and AP isolation logic dereferences this stale pointer, it triggers a use-after-free. The developers demonstrably understood the requirement—the VLAN header pointer is correctly reassigned in the same function—but the ethernet path was missed, likely because the developer was focused on the VLAN change and applied the fix locally without auditing unrelated header pointers in the same block. This 'local coherence without global coverage' failure mode is the operative risk. The fix is trivial (reassign `ethhdr` after `pskb_may_pull()`), but the structural question is whether batman-adv has other code paths with the same pattern: `pskb_may_pull()` followed by multiple skb header pointer dereferences where only some pointers were refreshed. Audit functions in the TX path, fragmentation handling, and multi-interface scenarios for this exact pattern. The deeper concern is that TT and AP isolation logic—which makes routing decisions affecting mesh topology—depends on this pointer, meaning the blast radius of a stale dereference extends beyond local crash to potential table state corruption propagating through the mesh protocol. For prioritization: treat any batman-adv code touching `pskb_may_pull()` with multiple header pointer accesses as high-risk until audited.
Practitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-72235 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data