{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2025-21766", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-29T08:45:45.762Z", "datePublished": "2025-02-27T02:18:16.570Z", "dateUpdated": "2026-08-05T11:54:19.559Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:54:19.559Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: use RCU protection in __ip_rt_update_pmtu()\n\n__ip_rt_update_pmtu() must use RCU protection to make\nsure the net structure it reads does not disappear." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.1, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - `__ip_rt_update_pmtu()` sits directly on the ICMP Fragmentation-Needed processing path — `icmp_rcv()` → `icmp_unreach()` → protocol err handlers (`udp_err`, `raw_err`, `ping_err`, `tcp_v4_err`, `ipip_err`, GRE/vti/esp/ah err) → `ipv4_sk_update_pmtu()`/`ipv4_update_pmtu()`. A remote host anywhere on the internet reaches it with a single crafted IPv4 ICMP packet, and the attacker-supplied `un.frag.mtu` becomes the value written into the FNHE entry.\nAC:H - The attacker fully controls the read side (unlimited ICMP frag-needed floods), but the freed `struct net` only becomes reachable when a namespace teardown races a long-lived cached `dst` whose `dst->dev` still maps to the dying netns — network-namespace destruction and the exact preemption window between loading `dev->nd_net` and dereferencing it are system state a remote attacker cannot induce.\nPR:N - No authentication or credentials are involved anywhere on the path; the tunnel error handlers (`ipip_err`, GRE, vti, esp4, ah4) and `icmp_err()` dispatch on the quoted inner header alone with no socket or peer verification, so any unauthenticated host can drive `ipv4_update_pmtu()`.\nUI:N - The ICMP error is consumed entirely inside softirq packet-receive processing; no local user opens, mounts, configures, or clicks anything for the vulnerable dereference to run.\nS:U - The use-after-free read and the resulting bogus FIB lookup and FNHE writes are all confined to the kernel's own security authority; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The freed `struct net` is not merely read for two sysctls — it is fed to `fib_lookup()`, which loads `net->ipv4.fib_main`/`fib_default`/`rules_ops` out of reclaimed memory and walks them as FIB tables and rule lists, so a groomed reallocation of the `net_cachep` object turns this into an attacker-directed read of arbitrary kernel addresses.\nI:H - `update_or_create_fnhe()` writes through the `fib_nh_common` returned by that poisoned lookup — `rcu_assign_pointer(nhc->nhc_exceptions, hash)`, `fnhe->fnhe_pmtu = pmtu`, `fnhe->fnhe_expires` — with `pmtu` taken verbatim from the attacker's `ntohs(icmph->un.frag.mtu)`, yielding a controlled write through a pointer chain rooted in freed memory.\nA:H - Even without weaponization, walking a FIB trie and a fib_rules list off a freed `struct net` reliably faults or corrupts state, producing a KASAN splat, oops, or panic, and the attacker can retrigger it indefinitely by replaying ICMP frag-needed packets." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/route.c" ], "versions": [ { "version": "2fbc6e89b2f1403189e624cabaf73e189c5e50c6", "lessThan": "ce3c6165fce0f06305c806696882a3ad4b90e33f", "status": "affected", "versionType": "git" }, { "version": "2fbc6e89b2f1403189e624cabaf73e189c5e50c6", "lessThan": "ea07480b23225942208f1b754fea1e7ec486d37e", "status": "affected", "versionType": "git" }, { "version": "2fbc6e89b2f1403189e624cabaf73e189c5e50c6", "lessThan": "9b1766d1ff5fe496aabe9fc5f4e34e53f35c11c4", "status": "affected", "versionType": "git" }, { "version": "2fbc6e89b2f1403189e624cabaf73e189c5e50c6", "lessThan": "4583748b65dee4d61bd50a2214715b4237bc152a", "status": "affected", "versionType": "git" }, { "version": "2fbc6e89b2f1403189e624cabaf73e189c5e50c6", "lessThan": "a39f61d212d822b3062d7f70fa0588e50e55664e", "status": "affected", "versionType": "git" }, { "version": "2fbc6e89b2f1403189e624cabaf73e189c5e50c6", "lessThan": "139512191bd06f1b496117c76372b2ce372c9a41", "status": "affected", "versionType": "git" }, { "version": "f415c264176e6095e9dee823e09c5bdd0ee0d337", "status": "affected", "versionType": "git" }, { "version": "98776a365da509ad923083ae54b38ee521c52742", "status": "affected", "versionType": "git" }, { "version": "860e2cc78c697c95bc749abb20047239fa1722ea", "status": "affected", "versionType": "git" }, { "version": "2b1be6c925cdf4638811765a9160796291494b89", "status": "affected", "versionType": "git" }, { "version": "4.14.200", "lessThan": "4.15", "status": "affected", "versionType": "semver" }, { "version": "4.19.148", "lessThan": "4.20", "status": "affected", "versionType": "semver" }, { "version": "5.4.68", "lessThan": "5.5", "status": "affected", "versionType": "semver" }, { "version": "5.8.12", "lessThan": "5.9", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/route.c" ], "versions": [ { "version": "5.9", "status": "affected" }, { "version": "0", "lessThan": "5.9", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.179", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.129", "lessThanOrEqual": "6.1.*", "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": "5.9", "versionEndExcluding": "5.15.179" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.1.129" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.6.79" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.12.16" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.13.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.9", "versionEndExcluding": "6.14" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.14.200" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.19.148" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.4.68" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.8.12" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ce3c6165fce0f06305c806696882a3ad4b90e33f" }, { "url": "https://git.kernel.org/stable/c/ea07480b23225942208f1b754fea1e7ec486d37e" }, { "url": "https://git.kernel.org/stable/c/9b1766d1ff5fe496aabe9fc5f4e34e53f35c11c4" }, { "url": "https://git.kernel.org/stable/c/4583748b65dee4d61bd50a2214715b4237bc152a" }, { "url": "https://git.kernel.org/stable/c/a39f61d212d822b3062d7f70fa0588e50e55664e" }, { "url": "https://git.kernel.org/stable/c/139512191bd06f1b496117c76372b2ce372c9a41" } ], "title": "ipv4: use RCU protection in __ip_rt_update_pmtu()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T19:37:21.502Z" } }, { "x_adpType": "supplier", "providerMetadata": { "orgId": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e", "shortName": "siemens-SADP", "dateUpdated": "2026-07-14T12:40:04.671Z" }, "affected": [ { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" }, { "vendor": "Siemens", "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP", "versions": [ { "status": "affected", "version": "V3.1.5", "lessThan": "*", "versionType": "custom" } ], "defaultStatus": "unknown" } ], "references": [ { "url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html" } ] } ] } }