CVE-2026-31630

Description

In the Linux kernel, the following vulnerability has been resolved: rxrpc: proc: size address buffers for %pISpc output The AF_RXRPC procfs helpers format local and remote socket addresses into fixed 50-byte stack buffers with "%pISpc". That is too small for the longest current-tree IPv6-with-port form the formatter can produce. In lib/vsprintf.c, the compressed IPv6 path uses a dotted-quad tail not only for v4mapped addresses, but also for ISATAP addresses via ipv6_addr_is_isatap(). As a result, a case such as [ffff:ffff:ffff:ffff:0:5efe:255.255.255.255]:65535 is possible with the current formatter. That is 50 visible characters, so 51 bytes including the trailing NUL, which does not fit in the existing char[50] buffers used by net/rxrpc/proc.c. Size the buffers from the formatter's maximum textual form and switch the call sites to scnprintf(). Changes since v1: - correct the changelog to cite the actual maximum current-tree case explicitly - frame the proof around the ISATAP formatting path instead of the earlier mapped-v4 example

Predictions

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

References

• https://git.kernel.org/stable/c/10ebed83f9f6414af4e85bc85ffaeda7effdd874
• https://git.kernel.org/stable/c/a44ce6aa2efb61fe44f2cfab72bb01544bbca272
• https://git.kernel.org/stable/c/db297c78ce537c9ac96f0eda9b25ad72c8caefa9
• https://www.suse.com/security/cve/CVE-2026-31630.html
• https://security-tracker.debian.org/tracker/CVE-2026-31630
• https://git.kernel.org/stable/c/235b2115de892eab2e107a42efa7a4347baaa80b
• https://git.kernel.org/stable/c/386c86412608d3449006a318a662cbcd6ca1f668
• https://git.kernel.org/stable/c/625af53a1564e31bb2df9adc3739df46137f46c1