{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-74656", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-74656", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-08-22T15:32:30.729Z", "updatedAt": "2026-10-16T19:16:07.512Z", "importedAt": "2026-10-24T01:58:30.346Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "ipv4: fix use-after-free in fib_nhc_update_mtu()", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fix use-after-free in fib_nhc_update_mtu()\n\nfib_nhc_update_mtu() walks the nexthop exception table under RTNL, but\nRTNL does not serialize this walk with PMTU exception updates. The walk\nuses rcu_dereference_protected() with a constant true condition without\nholding fnhe_lock.\n\nThe following interleaving can therefore occur:\n\n CPU 0 CPU 1\n fib_nhc_update_mtu() update_or_create_fnhe()\n load fnhe spin_lock_bh(&fnhe_lock)\n fnhe_remove_oldest()\n unlink fnhe\n kfree_rcu(fnhe, rcu)\n \n access fnhe after grace period\n\nKASAN reported:\n\n BUG: KASAN: slab-use-after-free in fib_nhc_update_mtu+0x3df/0x410\n Read of size 8 at addr ffff888107d49000 by task poc/90\n Call Trace:\n fib_nhc_update_mtu+0x3df/0x410\n fib_sync_mtu+0x7a/0xd0\n fib_netdev_event+0x229/0x3f0\n netif_set_mtu_ext+0x33a/0x570\n dev_set_mtu+0x88/0x120\n\nThe same walk updates fnhe_pmtu and fnhe_mtu_locked. These fields form a\npair and other writers serialize them with fnhe_lock. RCU alone prevents\nreclamation, but would still allow concurrent writers to leave a mixed\npair.\n\nWalk the table under RCU and acquire fnhe_lock only while updating each\nexception. RCU keeps the current entry alive while the short critical\nsection serializes its paired PMTU fields. This avoids holding the global\nlock while scanning all 2048 buckets for every nexthop.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "fd39e711866498ae94fcf9acf6f422a4f045b681" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "e1e602d6b22d5cb1641c4459c487eb18bf569e0a" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "e00f7d2b5f2540a3415a229c982af7a25ff6362e" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "dfe388da13aa784851e5ebbea90afbb099075761" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "5a28a4b22dde92f9d293b94236314b8d6181dc4a" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "63996ffc594d128ccec8fc0983f91effd2d3adc4" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "ed503eaad62f20cdd5122d7c3078a648a99c8f16" }, { "version": "af7d6cce53694a88d6a1bb60c9a239a6a5144459", "status": "affected", "versionType": "git", "lessThan": "bc5bde9ce3cc36502839dfe98e068f7303a50982" }, { "version": "b427832009b97a3ee412ef643a80b15372a7754d", "status": "affected", "versionType": "git" }, { "version": "2b7e4c735933be79882aba2bed9afa789e03c62f", "status": "affected", "versionType": "git" }, { "version": "8d59c3a6376bbc6dd3f7303968a719ffba75a4f1", "status": "affected", "versionType": "git" }, { "version": "9b4869cf385aa16f89c0f019eed4ec4e36aa441c", "status": "affected", "versionType": "git" }, { "version": "ff34695ced21e2dfa04d0fa1c5f6c35011fa8117", "status": "affected", "versionType": "git" }, { "version": "3.16.62", "status": "affected", "versionType": "semver", "lessThan": "3.17" }, { "version": "4.4.162", "status": "affected", "versionType": "semver", "lessThan": "4.5" }, { "version": "4.9.134", "status": "affected", "versionType": "semver", "lessThan": "4.10" }, { "version": "4.14.77", "status": "affected", "versionType": "semver", "lessThan": "4.15" }, { "version": "4.18.15", "status": "affected", "versionType": "semver", "lessThan": "4.19" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.19", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.19" }, { "version": "5.10.265", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.216", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.183", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.152", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.104", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.45", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.1.9", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }