CVE-2026-31630

Summary

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

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

Affected Software

VendorProductVersion RangeStatus
LinuxLinux75b54cb57ca34cbe7a87c6ac757c55360a624590 < 386c86412608d3449006a318a662cbcd6ca1f668affected
LinuxLinux75b54cb57ca34cbe7a87c6ac757c55360a624590 < 235b2115de892eab2e107a42efa7a4347baaa80baffected
LinuxLinux75b54cb57ca34cbe7a87c6ac757c55360a624590 < 625af53a1564e31bb2df9adc3739df46137f46c1affected
LinuxLinux75b54cb57ca34cbe7a87c6ac757c55360a624590 < db297c78ce537c9ac96f0eda9b25ad72c8caefa9affected
LinuxLinux75b54cb57ca34cbe7a87c6ac757c55360a624590 < 10ebed83f9f6414af4e85bc85ffaeda7effdd874affected
LinuxLinux75b54cb57ca34cbe7a87c6ac757c55360a624590 < a44ce6aa2efb61fe44f2cfab72bb01544bbca272affected
LinuxLinux4.9affected
LinuxLinux0 < 4.9unaffected
LinuxLinux5.10.258 <= 5.10.*unaffected
LinuxLinux5.15.209 <= 5.15.*unaffected
LinuxLinux6.1.175 <= 6.1.*unaffected
LinuxLinux6.18.23 <= 6.18.*unaffected
LinuxLinux6.19.13 <= 6.19.*unaffected
LinuxLinux7.0 <= *unaffected

Weaknesses

References