netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()

Summary

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.

Timeline

1. Apr 3, 2026, 3:15 PM UTCCVE published
2. Oct 16, 2026, 3:08 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: yes · Technical impact: partial

3. Oct 19, 2026, 6:35 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in 2121f5fbe88daff0f1fc5bc47d359426c74b86b0; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in 65fa92f79677858b14b9e4b7275f26639afe2710; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in 495e97af9e7249ee02b72bb1d0848a6efc3700f4; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in f5e4f4e4cdb75ec36802059a94195a31f193da60; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in 633e8f87dad32263f6a57dccdb873f042c062111; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in 9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in b652b05d51003ac074b912684f9ec7486231717b; From 5e35941d990123f155b02d5663e51a24f816b6f3 · fixed in f173d0f4c0f689173f8cdac79991043a4a89bf66

• Linux Linux

  2.6.17

• KernelLinux

  From 2.6.17 · fixed in 5.10.253; From 5.11.0 · fixed in 5.15.203; From 5.16.0 · fixed in 6.1.167; From 6.2.0 · fixed in 6.6.130; From 6.7.0 · fixed in 6.12.78; From 6.13.0 · fixed in 6.18.20; From 6.19.0 · fixed in 6.19.10

References 8