VulnerabilityPublished 25 Jun 2026Updated 6 Nov 2026

CVE-2026-53218: Linux kernel · netfilter: nft_exthdr: fix register tracking for F_PRESENT flag

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265 : update Linux kernel when convenient.

Data as of 6 Nov 2026, 16:49 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265, cd513e43b4b2bd1de39e2367bc4261c699a8652f, 19748967d59c31d24d21d40b728570788310b237 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783, < f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265	Fixed in f08fb3d42fd3aad0b7a263da3ac3ebaf0845e265
LinuxLinux	Affected ≥ c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783, < cd513e43b4b2bd1de39e2367bc4261c699a8652f	Fixed in cd513e43b4b2bd1de39e2367bc4261c699a8652f
LinuxLinux	Affected ≥ c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783, < 19748967d59c31d24d21d40b728570788310b237	Fixed in 19748967d59c31d24d21d40b728570788310b237
LinuxLinux	Affected ≥ c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783, < 78069a6d8bc86c9e036eb82c2af4a19cc1871a53	Fixed in 78069a6d8bc86c9e036eb82c2af4a19cc1871a53
LinuxLinux	Affected ≥ c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783, < 8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6	Fixed in 8738b1b6d0e639ca1fc0f61516afd3557ac4ecc6
LinuxLinux	Affected ≥ c078ca3b0c5bf82c2b31906c446d6e2ad8ea0783, < 772cecf198da732faebb5dcfc46d66a505be8495	Fixed in 772cecf198da732faebb5dcfc46d66a505be8495

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.

References

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