{ "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-2026-64109", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-64109", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-07-19T15:40:11.510Z", "updatedAt": "2026-10-19T20:28:12.212Z", "importedAt": "2026-10-24T01:58:25.636Z", "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": "af_unix: Fix UAF read of tail->len in unix_stream_data_wait()", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Fix UAF read of tail->len in unix_stream_data_wait()\n\nunix_stream_data_wait() does skb_peek_tail(&sk->sk_receive_queue) without\nholding any lock that prevents SKBs on that queue from being dequeued and\nfreed.\nThis has been the case since commit 79f632c71bea (\"unix/stream: fix\npeeking with an offset larger than data in queue\").\nThe first consequence of this is that the pointer comparison\n`tail != last` can be false even if `last` semantically refers to an\nalready-freed SKB while `tail` is a new SKB allocated at the same address;\nwhich can cause unix_stream_data_wait() to wrongly keep blocking after new\ndata has arrived, but only in a weird scenario where a peeking recv() and\na normal recv() on the same socket are racing, which is probably not a\nreal problem.\n\nBut since commit 2b514574f7e8 (\"net: af_unix: implement splice for stream\naf_unix sockets\"), `tail` is actually dereferenced, which can cause UAF in\nthe following race scenario (where test_setup() runs single-threaded,\nand afterwards, test_thread1() and test_thread2() run concurrently in\ntwo threads:\n```\nstatic int socks[2];\nvoid test_setup(void) {\n socketpair(AF_UNIX, SOCK_STREAM, 0, socks);\n send(socks[1], \"A\", 1, 0);\n int peekoff = 1;\n setsockopt(socks[0], SOL_SOCKET, SO_PEEK_OFF, &peekoff, sizeof(peekoff));\n}\nvoid test_thread1(void) {\n char dummy;\n recv(socks[0], &dummy, 1, MSG_PEEK);\n}\nvoid test_thread2(void) {\n char dummy;\n recv(socks[0], &dummy, 1, 0);\n shutdown(socks[1], SHUT_WR);\n}\n```\n\nwhen racing like this:\n```\nthread1 thread2\nunix_stream_read_generic\n mutex_lock(&u->iolock)\n skb_peek(&sk->sk_receive_queue)\n skb_peek_next(skb, &sk->sk_receive_queue)\n mutex_unlock(&u->iolock)\n unix_stream_read_generic\n unix_state_lock(sk)\n skb_peek(&sk->sk_receive_queue)\n unix_state_unlock(sk)\n unix_stream_data_wait\n unix_state_lock(sk)\n tail = skb_peek_tail(&sk->sk_receive_queue)\n spin_lock(&sk->sk_receive_queue.lock)\n __skb_unlink(skb, &sk->sk_receive_queue)\n spin_unlock(&sk->sk_receive_queue.lock)\n consume_skb(skb) [frees the SKB]\n `tail != last`: false\n `tail`: true\n `tail->len != last_len` ***UAF***\n```\n\nFix the UAF by removing the read of tail->len; checking tail->len would\nonly make sense if SKBs in the receive queue of a UNIX socket could grow,\nwhich can no longer happen.\n\nKuniyuki explained:\n\n> When commit 869e7c62486e (\"net: af_unix: implement stream sendpage\n> support\") added sendpage() support, data could be appended to the last\n> skb in the receiver's queue.\n>\n> That's why we needed to check if the length of the last skb was changed\n> while waiting for new data in unix_stream_data_wait().\n>\n> However, commit a0dbf5f818f9 (\"af_unix: Support MSG_SPLICE_PAGES\") and\n> commit 57d44a354a43 (\"unix: Convert unix_stream_sendpage() to use\n> MSG_SPLICE_PAGES\") refactored sendmsg(), and now data is always added\n> to a new skb.\n\nThat means this fix is not suitable for kernels before 6.5.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "2b514574f7e88c8498027ee366fd6e7aae5aa4b5", "status": "affected", "versionType": "git", "lessThan": "26342087fac93b3932e6af61dc91ec029cb8a623" }, { "version": "2b514574f7e88c8498027ee366fd6e7aae5aa4b5", "status": "affected", "versionType": "git", "lessThan": "38bccb927d83d7d52e5b20015a172a0b6101d11e" }, { "version": "2b514574f7e88c8498027ee366fd6e7aae5aa4b5", "status": "affected", "versionType": "git", "lessThan": "acdff9907478e82208475b1151700d0b71dcdc63" }, { "version": "2b514574f7e88c8498027ee366fd6e7aae5aa4b5", "status": "affected", "versionType": "git", "lessThan": "5f162f95a95834f06a8ec6140889272ad12e842f" }, { "version": "2b514574f7e88c8498027ee366fd6e7aae5aa4b5", "status": "affected", "versionType": "git", "lessThan": "be309f8eae8b474a4a617eaae01324da996fc719" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.2", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.2" }, { "version": "6.6.143", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.92", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.34", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.0.11", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }