CVE-2026-89783

/// Technical description

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/i

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References