CVE-2026-52999
Full vulnerability record from the local CVENow database.
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.
Severity
CRITICAL
CVSS score
9.1
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-06-24 17:17:10.913000
Last modified
2026-10-19 20:18:54.340000
View original CVE JSON
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-06-24T17:17:10.913",
"lastModified": "2026-10-19T20:18:54.340",
"vulnStatus": "Modified",
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nfnetlink_osf: fix out-of-bounds read on option matching\n\nIn nf_osf_match(), the nf_osf_hdr_ctx structure is initialized once\nand passed by reference to nf_osf_match_one() for each fingerprint\nchecked. During TCP option parsing, nf_osf_match_one() advances the\nshared ctx->optp pointer.\n\nIf a fingerprint perfectly matches, the function returns early without\nrestoring ctx->optp to its initial state. If the user has configured\nNF_OSF_LOGLEVEL_ALL, the loop continues to the next fingerprint.\nHowever, because ctx->optp was not restored, the next call to\nnf_osf_match_one() starts parsing from the end of the options buffer.\nThis causes subsequent matches to read garbage data and fail\nimmediately, making it impossible to log more than one match or logging\nincorrect matches.\n\nInstead of using a shared ctx->optp pointer, pass the context as a\nconstant pointer and use a local pointer (optp) for TCP option\ntraversal. This makes nf_osf_match_one() strictly stateless from the\ncaller's perspective, ensuring every fingerprint check starts at the\ncorrect option offset."
}
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