CVE-2026-89783: Linux Vulnerability (CVSS 9.8)

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/ipv6/xfrm6_input.c:309:10 index 6 is out of range for type 'xfrm_state *[6]'

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.21%

11.4th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 91fc387f63c00ddfb5221127a17bac97549a8343; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 68e8737fe8e72f085c608cff322b3d2de8340af1; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 8fe2c53fb81f5ad5be43af2ad09583f7c78b4b77; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < bdcda866c89f9a8b1acdabf02d26cde9fbe501d8; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 48996649222e95008cdb98cd58579e3fc8e5ee06; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 0f679e0523ddfff3fb554336ceb874b0e51e9cd3; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 5f35a29a5eed3d80befd32050843ac88dea3d61a; >= 9473e1f631de339c50bde1e3bd09e1045fe90fd5, < 5d9e3bf34fec9a5d237e4b7cef4a707bc2e091bc
Linux	Linux	2.6.25

References

Timeline

Published: Sep 16, 2026
Last Modified: Sep 16, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-89783?

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]'

How severe is CVE-2026-89783?

CVE-2026-89783 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.

How do I fix CVE-2026-89783?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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