{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-39962","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2025-04-16T07:20:57.149Z","datePublished":"2025-10-09T12:13:22.684Z","dateUpdated":"2026-08-05T12:06:31.023Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:06:31.023Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc: Fix untrusted unsigned subtract\n\nFix the following Smatch static checker warning:\n\n   net/rxrpc/rxgk_app.c:65 rxgk_yfs_decode_ticket()\n   warn: untrusted unsigned subtract. 'ticket_len - 10 * 4'\n\nby prechecking the length of what we're trying to extract in two places in\nthe token and decoding for a response packet.\n\nAlso use sizeof() on the struct we're extracting rather specifying the size\nnumerically to be consistent with the other related statements."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","baseScore":7.5,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable code parses RxGK RESPONSE packets received over UDP by an rxrpc server connection; the AFS cache manager (present on every kafs client) exposes this path to remote peers on the network.\nAC:L - A single crafted RESPONSE packet with a small token_len and oversized ticket_len reliably bypasses the check and triggers the crash; the required server key exists by default on the CM and kvno/enctype are standard, with no attacker-uncontrolled conditions.\nPR:N - The malformed length is processed during the challenge/response handshake (CONN_SERVICE_CHALLENGING), before any credential is verified, so no authentication or privileges are required.\nUI:N - Exploitation is fully driven by attacker-sent network packets; no action by any local user is needed.\nS:U - The impact is confined to the kernel that processes the packet; no crossing of a security/authority boundary such as VM or IOMMU escape occurs.\nC:N - The reliably reachable path is a BUG_ON crash with no data returned to the attacker; the OOB-read variant requires server-key knowledge to control decrypted content and its data is stored in a no-leak key, so there is no defensible information disclosure.\nI:N - The reachable outcome is a kernel panic in skb_to_sgvec; the length-check bypass does not yield an attacker-controlled write primitive (the payload allocation scales with the corrupted length), so no data modification results.\nA:H - The oversized attacker-controlled length reaches skb_to_sgvec and triggers BUG_ON(len), causing a kernel panic — a remote, unauthenticated denial of service."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxgk_app.c"],"versions":[{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","lessThan":"71571e187106631a8127f2dde780f35caa358d33","status":"affected","versionType":"git"},{"version":"9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a","lessThan":"2429a197648178cd4dc930a9d87c13c547460564","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/rxrpc/rxgk_app.c"],"versions":[{"version":"6.16","status":"affected"},{"version":"0","lessThan":"6.16","status":"unaffected","versionType":"semver"},{"version":"6.16.9","lessThanOrEqual":"6.16.*","status":"unaffected","versionType":"semver"},{"version":"6.17","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.16.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.16","versionEndExcluding":"6.17"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/71571e187106631a8127f2dde780f35caa358d33"},{"url":"https://git.kernel.org/stable/c/2429a197648178cd4dc930a9d87c13c547460564"}],"title":"rxrpc: Fix untrusted unsigned subtract","x_generator":{"engine":"bippy-1.2.0"}}}}