s390/ctcm: Prevent XID null dereference

Summary

In the Linux kernel, the following vulnerability has been resolved: s390/ctcm: Prevent XID null dereference The mpc_validate_xid() function sets grp->saved_xid2->xid2_flag2 to 0x40 to signal XID validation error. If peer XID is NULL or r/w channel pairing mismatch happens, grp->saved_xid2 is never initialized. An attempt to set the flag in such case leads to NULL dereference. Fix this by using the always available priv->xid->xid2_flag2 instead of grp->saved_xid2->xid2_flag2 for validation errors.

Timeline

1. Oct 28, 2026, 10:34 AM UTCCVE published
2. Oct 28, 2026, 10:41 AM UTCFirst seen by cve.now
3. Oct 30, 2026, 12:41 PM UTCRecord last updated

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  2.6.26

• KernelLinux

  From 2.6.26 · fixed in 6.18.59; From 6.19.0 · fixed in 7.2.13

References 8