{"id":"CVE-2026-74433","state":"PUBLISHED","title":"rxrpc: Fix UAF in rxgk_issue_challenge()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix UAF in rxgk_issue_challenge()\n\nFix rxgk_issue_challenge() to free the page containing the challenge\ncontent after invoking the tracepoint as the whdr passed to the tracepoint\npoints into the page just freed.","publishedAt":"2026-08-15T05:59:32.823Z","updatedAt":"2026-08-17T05:47:07.711Z","severity":{"score":9.8,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","status":"affected","lessThan":"844b8525ce503405c462ad67f750bec648720397","versionType":"git"},{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","status":"affected","lessThan":"83bb0ed050e2ad9453d8ef50e4d6e624eac6eed8","versionType":"git"},{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","status":"affected","lessThan":"107a4cb0d47e735830f852d83970d5c81f8e1e08","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxgk.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxgk.c"]}],"references":["https://git.kernel.org/stable/c/844b8525ce503405c462ad67f750bec648720397","https://git.kernel.org/stable/c/83bb0ed050e2ad9453d8ef50e4d6e624eac6eed8","https://git.kernel.org/stable/c/107a4cb0d47e735830f852d83970d5c81f8e1e08"],"weaknesses":[],"ingestedAt":"2026-10-29T20:12:58.252Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/74xxx/CVE-2026-74433.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74433","state":"PUBLISHED","datePublished":"2026-08-15T05:59:32.823Z","dateUpdated":"2026-08-17T05:47:07.711Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-08-15T05:44:03.896Z"},"containers":{"cna":{"title":"rxrpc: Fix UAF in rxgk_issue_challenge()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix UAF in rxgk_issue_challenge()\n\nFix rxgk_issue_challenge() to free the page containing the challenge\ncontent after invoking the tracepoint as the whdr passed to the tracepoint\npoints into the page just freed."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","status":"affected","lessThan":"844b8525ce503405c462ad67f750bec648720397","versionType":"git"},{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","status":"affected","lessThan":"83bb0ed050e2ad9453d8ef50e4d6e624eac6eed8","versionType":"git"},{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","status":"affected","lessThan":"107a4cb0d47e735830f852d83970d5c81f8e1e08","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxgk.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.16","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.16","versionType":"semver"},{"version":"6.18.40","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.5","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxgk.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/844b8525ce503405c462ad67f750bec648720397"},{"url":"https://git.kernel.org/stable/c/83bb0ed050e2ad9453d8ef50e4d6e624eac6eed8"},{"url":"https://git.kernel.org/stable/c/107a4cb0d47e735830f852d83970d5c81f8e1e08"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The bug is in rxgk_issue_challenge() on the RxRPC server path reached when a remote UDP RxRPC DATA packet starts a new call; packets enter via rxrpc_encap_rcv() and the I/O thread, then conn_event processing issues an RxGK challenge during the pre-auth handshake on internet-facing AFS/RxGK servers.\nAC:L - Once an RxGK-enabled AFS kernel server is reachable, an attacker can reliably trigger rxgk_issue_challenge() by sending a valid incoming DATA packet with security index YFS-RxGK; the UAF is deterministic on each successful challenge transmission and does not depend on winning a race.\nPR:N - The vulnerable code runs during initial server-side connection setup before client credentials are verified: an unauthenticated remote peer that can reach the RxRPC UDP port can force challenge issuance without any local account, capability, or namespace privilege on the target.\nUI:N - Exploitation requires only network packets to the RxRPC listener; no victim user action such as opening files, mounting AFS, or enabling tracing is needed for the server to automatically enter the challenging path and hit the bug.\nS:U - Impact is confined to kernel memory integrity and availability on the AFS/RxRPC server host; it does not by itself cross a VM, container, or IOMMU security boundary, though it may enable local privilege escalation on that host.\nC:H - This is a use-after-free: __free_page() releases the challenge buffer before trace_rxrpc_tx_packet() dereferences whdr pointing into that page, enabling reads of freed slab/page memory and potential disclosure of kernel heap contents exploitable for KASLR bypass.\nI:H - UAF on the challenge transmit path can be leveraged with heap grooming to obtain controlled reuse of the freed page and build arbitrary kernel write or control-flow hijack primitives, not merely a bounded protocol corruption.\nA:H - Reading or reusing freed kernel pages during challenge handling can provoke kernel oops/panic or wedged RxRPC/AFS service state; repeated remote triggering of the handshake can deny availability of the file service even without full exploitation."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-17T05:47:07.711Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.18.40"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.1.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}