CVE-2026-52993: Linux kernel · tipc: fix double-free in tipc_buf_append()
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in d3556656c6daebf8def751c7e71d11dd0a180d24 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in d3556656c6daebf8def751c7e71d11dd0a180d24, d293ca716e7d5dffdaecaf6b9b2f857a33dc3d3a, a438975a6dcdbd70865978c021650d1485586f0b +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
| LinuxLinux | Affected
| Fixed in
|
Description
In the Linux kernel, the following vulnerability has been resolved: tipc: fix double-free in tipc_buf_append() tipc_msg_validate() can potentially reallocate the skb it is validating, freeing the old one. In tipc_buf_append(), it was being called with a pointer to a local variable which was a copy of the caller's skb pointer. If the skb was reallocated and validation subsequently failed, the error handling path would free the original skb pointer, which had already been freed, leading to double-free. Fix this by checking if head now points to a newly allocated reassembled skb. If it does, reassign *headbuf for later freeing operations.
References
- git.kernel.org/stable/c/a438975a6dcdbd70865978c021650d1485586f0b (opens in a new tab)
- git.kernel.org/stable/c/4ee4deadaae7cb2e3d53af0fc889cf92a73413c0 (opens in a new tab)
- git.kernel.org/stable/c/d3556656c6daebf8def751c7e71d11dd0a180d24 (opens in a new tab)
- git.kernel.org/stable/c/0274f24485fc38032d4093e463dc3ff5c7a667c9 (opens in a new tab)
- git.kernel.org/stable/c/4d104882bc815d4ec666ace9155f5f52715879a6 (opens in a new tab)
- git.kernel.org/stable/c/1d5e589055880fae229e229e1929e087dbe08cf3 (opens in a new tab)
- git.kernel.org/stable/c/29940fff14110ca48c5ccc168d121665b51bb778 (opens in a new tab)
- git.kernel.org/stable/c/d293ca716e7d5dffdaecaf6b9b2f857a33dc3d3a (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-52993 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2492437 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52993.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:47017 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:49212 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:45115 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:45116 (opens in a new tab)