netfilter: xt_connmark: reject invalid shift parameters

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: xt_connmark: reject invalid shift parameters Revision 2 of the CONNMARK target accepts user-controlled shift parameters and applies them to 32-bit mark values in connmark_tg_shift(). A shift_bits value of 32 or more triggers an undefined-shift bug when the rule is evaluated. Invalid shift_dir values are also accepted and silently fall back to the left-shift path. Reject invalid revision-2 shift parameters in connmark_tg_check() so malformed rules fail at installation time, before they can reach the packet path.

Timeline

1. Aug 15, 2026, 5:55 AM UTCCVE published
2. Oct 16, 2026, 6:47 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Oct 16, 2026, 6:55 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 472a73e00757b971d613d796374d2727b2e4954d · fixed in d8ce63d928b457fba7ed1e302492dfd32293671c; From 472a73e00757b971d613d796374d2727b2e4954d · fixed in 9657bb11a6376ab0a79f05d433713d6944111e9d; From 472a73e00757b971d613d796374d2727b2e4954d · fixed in 8ace320ac4416f5e5fbcd065309fb2dfcce787b0; From 472a73e00757b971d613d796374d2727b2e4954d · fixed in c3fa852d117b3fda72265e4230e3967db4a74fcf; From 472a73e00757b971d613d796374d2727b2e4954d · fixed in 4eef84b09a3836919360c4232b0f16651a155eec; From 472a73e00757b971d613d796374d2727b2e4954d · fixed in 230173cc6105bdfb2696d37e6e56687b003fbe63; From 472a73e00757b971d613d796374d2727b2e4954d · fixed in 1b47026fb4b35bac850ad6e8a4ad7fc018e09ebc

• Linux Linux

  4.17

• KernelLinux

  From 4.17.0 · fixed in 5.15.212; From 5.16.0 · fixed in 6.1.178; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5

References 7