CVE-2026-53218

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag nft_exthdr_init() passes user-controlled priv->len to nft_parse_register_store(), which marks that many bytes in the register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT is set, the eval paths write only 1 byte (nft_reg_store8) or 4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nft_regs. Bail out if userspace requests too much data when F_PRESENT is set.

EPSS — Exploit Prediction

0.0013

Probability of exploitation

0.03%

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/19748967d59c31d24d21d40b728570788310b237 https://git.kernel.org/stable/c/46fc15a044e9938e7ea77786fb37edd2cd74f031 https://git.kernel.org/stable/c/67b27434c43b68a97becda98c9f0c8cf6cba2134 https://git.kernel.org/stable/c/772cecf198da732faebb5dcfc46d66a505be8495 https://git.kernel.org/stable/c/78069a6d8bc86c9e036eb82c2af4a19cc1871a53 https://git.kernel.org/stable/c/8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6 https://git.kernel.org/stable/c/cd513e43b4b2bd1de39e2367bc4261c699a8652f https://git.kernel.org/stable/c/f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265

Frequently Asked Questions

What is CVE-2026-53218? +

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_exthdr: fix register tracking for F_PRESENT flag nft_exthdr_init() passes user-controlled priv->len to nft_parse_register_store(), which marks that many bytes in the register bitmap as initialized. However, when NFT_EXTHDR_F_PRESENT is set, the eval paths write only 1 byte (nft_reg_store8) or 4 bytes (*dest = 0 on TCP/DCCP error path). When len > 4, registers beyond the first are never written, retaining uninitialized stack data from nft_regs. Bail out if userspace requests too much data when F_PRESENT is set.

How do I check if I'm vulnerable to CVE-2026-53218? +

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.

Description

EPSS — Exploit Prediction

References

Other References

Frequently Asked Questions

Don't wait for an exploit