{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-53250","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-06-09T07:44:35.394Z","datePublished":"2026-06-25T08:39:42.630Z","dateUpdated":"2026-08-05T12:34:33.657Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T12:34:33.657Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nxsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()\n\nThe TX metadata area resides in the UMEM buffer which is memory-mapped\nand concurrently writable by userspace. In xsk_skb_metadata(),\ncsum_start and csum_offset are read from shared memory for bounds\nvalidation, then read again for skb assignment. A malicious userspace\napplication can race to overwrite these values between the two reads,\nbypassing the bounds check and causing out-of-bounds memory access\nduring checksum computation in the transmit path.\n\nFix this by reading csum_start and csum_offset into local variables\nonce, then using the local copies for both validation and assignment.\n\nNote that other metadata fields (flags, launch_time) and the cached\ncsum fields may be mutually inconsistent due to concurrent userspace\nwrites, but this is benign: the only security-critical invariant is\nthat each field's validated value is the same one used, which local\ncaching guarantees."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The vulnerable path is reached by a local process using AF_XDP socket setup, UMEM registration, TX ring submission, and send/poll-driven transmit; it is not reachable directly from remote network packets.\nAC:L - The attacker controls the UMEM metadata and can trigger TX from the same process, so the TOCTOU race can be created with attacker-controlled concurrent writes.\nPR:L - AF_XDP socket creation requires CAP_NET_RAW in the relevant network namespace, which is attainable by a low-privileged local user in user/network namespace deployments.\nUI:N - No victim action is needed after the attacker has local execution; the attacker sets up the socket, UMEM, metadata, and transmit operation directly.\nS:U - The vulnerability corrupts or reads kernel networking memory within the same kernel security authority; this is standard local kernel attack surface, not a VM or hardware boundary crossing.\nC:H - Racing csum_start/csum_offset can bypass validation and drive out-of-bounds checksum reads in kernel transmit checksum handling, so potential kernel memory disclosure is high.\nI:H - The same unvalidated checksum offsets can cause checksum writes to an attacker-influenced out-of-bounds location relative to skb data, making kernel memory corruption plausible.\nA:H - The out-of-bounds memory access in the kernel transmit path can trigger warnings, faults, or kernel crashes and can be repeatedly exercised by the local attacker."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/xdp/xsk.c"],"versions":[{"version":"48eb03dd26304c24f03bdbb9382e89c8564e71df","lessThan":"0dfe05b938435892875e07771170051346412df9","status":"affected","versionType":"git"},{"version":"48eb03dd26304c24f03bdbb9382e89c8564e71df","lessThan":"bfdfd2706d5fb2cd496a1506e680daf979309c8b","status":"affected","versionType":"git"},{"version":"48eb03dd26304c24f03bdbb9382e89c8564e71df","lessThan":"22ba97ea9cc1f63a0d0244fae38057ed452b6ac7","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/xdp/xsk.c"],"versions":[{"version":"6.8","status":"affected"},{"version":"0","lessThan":"6.8","status":"unaffected","versionType":"semver"},{"version":"6.18.36","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.0.13","lessThanOrEqual":"7.0.*","status":"unaffected","versionType":"semver"},{"version":"7.1","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":"6.8","versionEndExcluding":"6.18.36"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.0.13"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.8","versionEndExcluding":"7.1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/0dfe05b938435892875e07771170051346412df9"},{"url":"https://git.kernel.org/stable/c/bfdfd2706d5fb2cd496a1506e680daf979309c8b"},{"url":"https://git.kernel.org/stable/c/22ba97ea9cc1f63a0d0244fae38057ed452b6ac7"}],"title":"xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()","x_generator":{"engine":"bippy-1.2.0"}}}}