CVE-2026-52993 (CVSS 9.8)

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.

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CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0036

Probability of exploitation

0.28%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-763 CWE-763

References

Other References

https://git.kernel.org/stable/c/0274f24485fc38032d4093e463dc3ff5c7a667c9 https://git.kernel.org/stable/c/1d5e589055880fae229e229e1929e087dbe08cf3 https://git.kernel.org/stable/c/29940fff14110ca48c5ccc168d121665b51bb778 https://git.kernel.org/stable/c/4d104882bc815d4ec666ace9155f5f52715879a6 https://git.kernel.org/stable/c/4ee4deadaae7cb2e3d53af0fc889cf92a73413c0 https://git.kernel.org/stable/c/a438975a6dcdbd70865978c021650d1485586f0b https://git.kernel.org/stable/c/d293ca716e7d5dffdaecaf6b9b2f857a33dc3d3a https://git.kernel.org/stable/c/d3556656c6daebf8def751c7e71d11dd0a180d24 https://access.redhat.com/security/cve/CVE-2026-52993 https://bugzilla.redhat.com/show_bug.cgi?id=2492437

Frequently Asked Questions

What is CVE-2026-52993? +

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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-52993? +

CVE-2026-52993 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0036, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-52993? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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