{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21789", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.766Z", "datePublished": "2025-02-27T02:18:27.817Z", "dateUpdated": "2026-08-05T11:54:27.092Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:54:27.092Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nLoongArch: csum: Fix OoB access in IP checksum code for negative lengths\n\nCommit 69e3a6aa6be2 (\"LoongArch: Add checksum optimization for 64-bit\nsystem\") would cause an undefined shift and an out-of-bounds read.\n\nCommit 8bd795fedb84 (\"arm64: csum: Fix OoB access in IP checksum code\nfor negative lengths\") fixes the same issue on ARM64." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H", "baseScore": 7.3, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The negative length originates from skb metadata (csum_start vs. transport header offset) that the attacker sets locally via an AF_PACKET/tun socket with virtio_net_hdr, not from remote packet header fields — every RX path that derives lengths from peer-supplied headers validates them first (e.g. `tcf_csum_skb_nextlayer()`'s `ipl < hl` check). Exploitation therefore requires local socket API access.\nAC:L - The attacker deterministically chooses csum_start, csum_offset and gso_size in the virtio_net_hdr and immediately drives the packet through the GSO segmentation path; there is no race, no memory-layout dependency, and no state outside the attacker's control.\nPR:L - An unprivileged local user can obtain CAP_NET_RAW in a new user+network namespace (`unshare -Urn`) and open the AF_PACKET socket needed to inject the crafted virtio_net_hdr; no real root and no init-namespace capability is required.\nUI:N - The entire sequence is a single sendmsg() by the attacker's own process; no victim action, mount, or file open is involved.\nS:U - The out-of-bounds read stays within the kernel's own address space and security authority — there is no VM, IOMMU, or sandbox boundary crossed.\nC:H - This is a slab-out-of-bounds read (KASAN reports it as an unbounded ~4 GB read) whose out-of-bounds bytes are folded into the checksum that is then written into the outgoing packet header and transmitted, giving the attacker an observable channel onto adjacent kernel heap contents.\nI:L - The undefined shift makes the tail-masking meaningless, so a corrupted checksum is computed from out-of-bounds data and stored into the transmitted packet's checksum field; this modifies network data but yields no kernel memory write primitive.\nA:H - On KASAN/UBSAN-instrumented kernels the negative length produces a slab-out-of-bounds report and an undefined-shift splat that panics under the widely deployed panic_on_warn setting, and the huge shadow-memory scan from `kasan_check_read()` with a ~4 GB size makes an oops the expected outcome." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/loongarch/lib/csum.c" ], "versions": [ { "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c", "lessThan": "964a8895704a22efc06a2a3276b624a5ae985a06", "status": "affected", "versionType": "git" }, { "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c", "lessThan": "9f15a8df542c0f08732a67d1a14ee7c22948fb97", "status": "affected", "versionType": "git" }, { "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c", "lessThan": "d6508ffff32b44b6d0de06704034e4eef1c307a7", "status": "affected", "versionType": "git" }, { "version": "69e3a6aa6be21de6aaf38130fad97ecde34a193c", "lessThan": "6287f1a8c16138c2ec750953e35039634018c84a", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "arch/loongarch/lib/csum.c" ], "versions": [ { "version": "6.4", "status": "affected" }, { "version": "0", "lessThan": "6.4", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.79", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.16", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13.4", "lessThanOrEqual": "6.13.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.14", "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": "6.4", "versionEndExcluding": "6.6.79" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.12.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.13.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.4", "versionEndExcluding": "6.14" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/964a8895704a22efc06a2a3276b624a5ae985a06" }, { "url": "https://git.kernel.org/stable/c/9f15a8df542c0f08732a67d1a14ee7c22948fb97" }, { "url": "https://git.kernel.org/stable/c/d6508ffff32b44b6d0de06704034e4eef1c307a7" }, { "url": "https://git.kernel.org/stable/c/6287f1a8c16138c2ec750953e35039634018c84a" } ], "title": "LoongArch: csum: Fix OoB access in IP checksum code for negative lengths", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.1, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2025-21789", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2025-10-01T19:29:57.287707Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-125", "description": "CWE-125 Out-of-bounds Read" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-10-01T19:36:39.729Z" } } ] } }