CVE-2026-52999
Linux Kernel out-of-bounds read
- Published24 Jun 2026
Description
In the Linux kernel, the following vulnerability has been resolved: netfilter: nfnetlink_osf: fix out-of-bounds read on option matching In nf_osf_match(), the nf_osf_hdr_ctx structure is initialized once and passed by reference to nf_osf_match_one() for each fingerprint checked. During TCP option parsing, nf_osf_match_one() advances the shared ctx->optp pointer. If a fingerprint perfectly matches, the function returns early without restoring ctx->optp to its initial state. If the user has configured NF_OSF_LOGLEVEL_ALL, the loop continues to the next fingerprint. However, because ctx->optp was not restored, the next call to nf_osf_match_one() starts parsing from the end of the options buffer. This causes subsequent matches to read garbage data and fail immediately, making it impossible to log more than one match or logging incorrect matches. Instead of using a shared ctx->optp pointer, pass the context as a constant pointer and use a local pointer (optp) for TCP option traversal. This makes nf_osf_match_one() strictly stateless from the caller's perspective, ensuring every fingerprint check starts at the correct option offset.
CVSS 3.1 breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:HAffected products
Remediation
- https://git.kernel.org/stable/c/0145548346c4a30981a870a8ca00eac46ba27e85
- https://git.kernel.org/stable/c/1c136f2c44a5913646bac85303612fd0825197a0
- https://git.kernel.org/stable/c/1e19a07291bb8682c14c39a64725a3ae54ab8ccc
- https://git.kernel.org/stable/c/21883587593d7c8bb519a79460a0b5bc5ffbdabd
- https://git.kernel.org/stable/c/32e50f92c7cf3f4eba29622179a5fcdc2aebab41
- https://git.kernel.org/stable/c/70a3f31d25cf2ec9d4ddfa408120171ead955623
References
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://git.kernel.org/stable/c/0145548346c4a30981a870a8ca00eac46ba27e85
- https://git.kernel.org/stable/c/1c136f2c44a5913646bac85303612fd0825197a0
- https://git.kernel.org/stable/c/1e19a07291bb8682c14c39a64725a3ae54ab8ccc
- https://git.kernel.org/stable/c/21883587593d7c8bb519a79460a0b5bc5ffbdabd
- https://git.kernel.org/stable/c/32e50f92c7cf3f4eba29622179a5fcdc2aebab41
- https://git.kernel.org/stable/c/70a3f31d25cf2ec9d4ddfa408120171ead955623
- https://git.kernel.org/stable/c/edb78a142d2e5948e63647c0646aa7e7886935f0
- https://git.kernel.org/stable/c/f5ca450087c3baf3651055e7a6de92600f827af3
Related CVEs
Recent high-severity vulnerabilities sharing a weakness type.
Frequently asked
Is CVE-2026-52999 being actively exploited?
CVE-2026-52999 is not in the CISA KEV catalog. Its EPSS exploit probability is 0.82%.
How severe is CVE-2026-52999?
CVE-2026-52999 has a CVSS 3.1 base score of 9.1, rated critical. EPSS estimates a 0.82% probability of exploitation.
Which products are affected by CVE-2026-52999?
Affected products include Linux Kernel.
How do I fix CVE-2026-52999?
Upgrade affected software to a fixed version, for example Linux Kernel 4.20 or later, then confirm no affected versions remain in your inventory.
How Secuno handles this
Secuno correlates vulnerabilities like CVE-2026-52999 against the real software inventory on every managed device, as each hourly inventory arrives. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.
Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.