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CVE-2026-89783: Linux

Severity

9.8 (CRITICAL)

Vendor

LINUX

Affected versions

9473e1f631de339c50bde1e3bd09e1045fe90fd5 through before 91fc387f63c00ddfb5221127a17bac97549a8343; 9473e1f631de339c50bde1

Patch status

Patched

Published

2026-09-16T09:17:08.930

Modified

2026-09-16T15:18:08.720

Why it matters

Critical vulnerability requiring immediate validation against your environment.

Recommended admin actions

• Prioritize validation immediately due to critical CVSS severity.

Technical summary

In the Linux kernel, the following vulnerability has been resolved: xfrm6: fix out-of-bounds write in xfrm6_input_addr() when secpath is full The depth check in xfrm6_input_addr() is off by one: if (1 + sp->len == XFRM_MAX_DEPTH) goto drop; … sp->xvec[sp->len++] = x; xfrm_input() can leave sp->len == XFRM_MAX_DEPTH, and the transport-mode receive path re-enters IPv6 input via xfrm_trans_reinject() with that secpath preserved. If the inner packet carries a destination-options HAO option or a type-2 routing header, xfrm6_input_addr() is called with sp->len == XFRM_MAX_DEPTH; the check (1 + 6 == 6) is false, so sp->xvec[sp->len++] writes one slot past the 6-element xvec[]. The write stays within the sec_path allocation (invisible to KASAN); UBSAN_BOUNDS flags it and panics under panic_on_warn. Use "sp->len >= XFRM_MAX_DEPTH", matching xfrm_input(). This also restores one chain level the old check rejected at sp->len == 5. UBSAN: array-index-out-of-bounds in net/ipv6/xfrm6_input.c:309:10 index 6 is out of range for type 'xfrm_state *[6]'

View the official NVD record for CVE-2026-89783

CVE data is sourced from NVD/CNA records and optional enrichment. Validate against the vendor advisory before taking production action.