CVE-2026-63912 (CVSS 9.8)

Description

In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: restore combined single-frag length gate The ESP out-of-place fast path appends the trailer in esp_output_head() before esp_output_tail() allocates the destination page frag. The head-side gate currently checks skb->data_len and tailen separately, but the tail code allocates a single destination frag from the combined post-trailer skb->data_len. Reject the page-frag fast path when the combined aligned length exceeds a page. Otherwise skb_page_frag_refill() may fall back to a single page while the destination sg still spans the combined skb->data_len. Restore this combined-length page gate for both IPv4 and IPv6.

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CVSS v3.1 Score

9.8

CRITICAL

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

EPSS — Exploit Prediction

0.0070

Probability of exploitation

0.49%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/322e48187e0245ab2fff6fec2220b0cae677dbec https://git.kernel.org/stable/c/36519e3d941fc99d3b52c134dbaf311f987a4708 https://git.kernel.org/stable/c/566295735530ee513326049b0540f32ec050bf2e https://git.kernel.org/stable/c/5d7ab86e2b6bc23054616bf6ac562013bf60af8c https://git.kernel.org/stable/c/65f3b3fc2347b89fe21db1e92c7681368415f095 https://git.kernel.org/stable/c/b84091ceddc9f133229dceab3ccc930bf27f9cba https://git.kernel.org/stable/c/c093468aea8277f77272a4f199b2e15e19cabb59 https://git.kernel.org/stable/c/dfa0d7b0ff1eb6b2c416b8fdb9b4f2cefba57a40

Frequently Asked Questions

What is CVE-2026-63912? +

In the Linux kernel, the following vulnerability has been resolved: xfrm: esp: restore combined single-frag length gate The ESP out-of-place fast path appends the trailer in esp_output_head() before esp_output_tail() allocates the destination page frag. The head-side gate currently checks skb->data_len and tailen separately, but the tail code allocates a single destination frag from the combined post-trailer skb->data_len. Reject the page-frag fast path when the combined aligned length exceeds a page. Otherwise skb_page_frag_refill() may fall back to a single page while the destination sg still spans the combined skb->data_len. Restore this combined-length page gate for both IPv4 and IPv6. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2026-63912? +

CVE-2026-63912 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately. The EPSS score is 0.0070, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-63912? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

CVE-2026-63912