CVE-2026-23319 (GCVE-0-2026-23319)

Vulnerability from cvelistv5 – Published: 2026-03-25 10:27 – Updated: 2026-04-13 06:04
VLAI?
Title
bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim The root cause of this bug is that when 'bpf_link_put' reduces the refcount of 'shim_link->link.link' to zero, the resource is considered released but may still be referenced via 'tr->progs_hlist' in 'cgroup_shim_find'. The actual cleanup of 'tr->progs_hlist' in 'bpf_shim_tramp_link_release' is deferred. During this window, another process can cause a use-after-free via 'bpf_trampoline_link_cgroup_shim'. Based on Martin KaFai Lau's suggestions, I have created a simple patch. To fix this: Add an atomic non-zero check in 'bpf_trampoline_link_cgroup_shim'. Only increment the refcount if it is not already zero. Testing: I verified the fix by adding a delay in 'bpf_shim_tramp_link_release' to make the bug easier to trigger: static void bpf_shim_tramp_link_release(struct bpf_link *link) { /* ... */ if (!shim_link->trampoline) return; + msleep(100); WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline, NULL)); bpf_trampoline_put(shim_link->trampoline); } Before the patch, running a PoC easily reproduced the crash(almost 100%) with a call trace similar to KaiyanM's report. After the patch, the bug no longer occurs even after millions of iterations.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e , < 529e685e522b9d7fb379dbe6929dcdf520e34c8c (git)
Affected: 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e , < 9b02c5c4147f8af8ed783c8deb5df927a55c3951 (git)
Affected: 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e , < cfcfa0ca0212162aa472551266038e8fd6768cff (git)
Affected: 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e , < 3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2 (git)
Affected: 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e , < 4e8a0005d633a4adc98e3b65d5080f93b90d356b (git)
Affected: 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e , < 56145d237385ca0e7ca9ff7b226aaf2eb8ef368b (git)
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    Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.1.167 , ≤ 6.1.* (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.77 , ≤ 6.12.* (semver)
Unaffected: 6.18.17 , ≤ 6.18.* (semver)
Unaffected: 6.19.7 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim\n\nThe root cause of this bug is that when \u0027bpf_link_put\u0027 reduces the\nrefcount of \u0027shim_link-\u003elink.link\u0027 to zero, the resource is considered\nreleased but may still be referenced via \u0027tr-\u003eprogs_hlist\u0027 in\n\u0027cgroup_shim_find\u0027. The actual cleanup of \u0027tr-\u003eprogs_hlist\u0027 in\n\u0027bpf_shim_tramp_link_release\u0027 is deferred. During this window, another\nprocess can cause a use-after-free via \u0027bpf_trampoline_link_cgroup_shim\u0027.\n\nBased on Martin KaFai Lau\u0027s suggestions, I have created a simple patch.\n\nTo fix this:\n   Add an atomic non-zero check in \u0027bpf_trampoline_link_cgroup_shim\u0027.\n   Only increment the refcount if it is not already zero.\n\nTesting:\n   I verified the fix by adding a delay in\n   \u0027bpf_shim_tramp_link_release\u0027 to make the bug easier to trigger:\n\nstatic void bpf_shim_tramp_link_release(struct bpf_link *link)\n{\n\t/* ... */\n\tif (!shim_link-\u003etrampoline)\n\t\treturn;\n\n+\tmsleep(100);\n\tWARN_ON_ONCE(bpf_trampoline_unlink_prog(\u0026shim_link-\u003elink,\n\t\tshim_link-\u003etrampoline, NULL));\n\tbpf_trampoline_put(shim_link-\u003etrampoline);\n}\n\nBefore the patch, running a PoC easily reproduced the crash(almost 100%)\nwith a call trace similar to KaiyanM\u0027s report.\nAfter the patch, the bug no longer occurs even after millions of\niterations."
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    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23319\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-03-25T11:16:28.570\",\"lastModified\":\"2026-04-23T21:05:38.103\",\"vulnStatus\":\"Analyzed\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nbpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim\\n\\nThe root cause of this bug is that when \u0027bpf_link_put\u0027 reduces the\\nrefcount of \u0027shim_link-\u003elink.link\u0027 to zero, the resource is considered\\nreleased but may still be referenced via \u0027tr-\u003eprogs_hlist\u0027 in\\n\u0027cgroup_shim_find\u0027. The actual cleanup of \u0027tr-\u003eprogs_hlist\u0027 in\\n\u0027bpf_shim_tramp_link_release\u0027 is deferred. During this window, another\\nprocess can cause a use-after-free via \u0027bpf_trampoline_link_cgroup_shim\u0027.\\n\\nBased on Martin KaFai Lau\u0027s suggestions, I have created a simple patch.\\n\\nTo fix this:\\n   Add an atomic non-zero check in \u0027bpf_trampoline_link_cgroup_shim\u0027.\\n   Only increment the refcount if it is not already zero.\\n\\nTesting:\\n   I verified the fix by adding a delay in\\n   \u0027bpf_shim_tramp_link_release\u0027 to make the bug easier to trigger:\\n\\nstatic void bpf_shim_tramp_link_release(struct bpf_link *link)\\n{\\n\\t/* ... */\\n\\tif (!shim_link-\u003etrampoline)\\n\\t\\treturn;\\n\\n+\\tmsleep(100);\\n\\tWARN_ON_ONCE(bpf_trampoline_unlink_prog(\u0026shim_link-\u003elink,\\n\\t\\tshim_link-\u003etrampoline, NULL));\\n\\tbpf_trampoline_put(shim_link-\u003etrampoline);\\n}\\n\\nBefore the patch, running a PoC easily reproduced the crash(almost 100%)\\nwith a call trace similar to KaiyanM\u0027s report.\\nAfter the patch, the bug no longer occurs even after millions of\\niterations.\"},{\"lang\":\"es\",\"value\":\"En el n\u00facleo de Linux, se ha solucionado la siguiente vulnerabilidad: bpf: Correcci\u00f3n de un problema de UAF en bpf_trampoline_link_cgroup_shim. La causa principal de este error es que, cuando \u00abbpf_link_put\u00bb reduce a cero el contador de referencias de \u00abshim_link-\u0026gt;link.link\u00bb, el recurso se considera liberado, pero a\u00fan puede ser referenciado a trav\u00e9s de \u00abtr-\u0026gt;progs_hlist\u00bb en \u00abcgroup_shim_find\u00bb. La limpieza real de \u00abtr-\u0026gt;progs_hlist\u00bb en \u00abbpf_shim_tramp_link_release\u00bb se aplaza. Durante este intervalo, otro proceso puede provocar un uso despu\u00e9s de la liberaci\u00f3n a trav\u00e9s de \u00abbpf_trampoline_link_cgroup_shim\u00bb. Bas\u00e1ndome en las sugerencias de Martin KaFai Lau, he creado un parche sencillo. Para solucionar esto: a\u00f1adir una comprobaci\u00f3n at\u00f3mica de que no sea cero en \u00abbpf_trampoline_link_cgroup_shim\u00bb. Solo incrementar el contador de referencias si a\u00fan no es cero. Pruebas: He verificado la correcci\u00f3n a\u00f1adiendo un retraso en \u00abbpf_shim_tramp_link_release\u00bb para que el error sea m\u00e1s f\u00e1cil de provocar: static void bpf_shim_tramp_link_release(struct bpf_link *link) { /* ... */ if (!shim_link-\u0026gt;trampoline) return; + msleep(100); WARN_ON_ONCE(bpf_trampoline_unlink_prog(\u0026amp;shim_link-\u0026gt;link, shim_link-\u0026gt;trampoline, NULL)); bpf_trampoline_put(shim_link-\u0026gt;trampoline); } Antes del parche, al ejecutar un PoC se reproduc\u00eda f\u00e1cilmente el bloqueo (casi al 100 %) con un seguimiento de llamadas similar al del informe de KaiyanM. Tras el parche, el error ya no se produce ni siquiera tras millones de iteraciones.\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"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\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.0.1\",\"versionEndExcluding\":\"6.1.167\",\"matchCriteriaId\":\"72B24488-A57B-4D9C-A7EA-A6020518455B\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.130\",\"matchCriteriaId\":\"C57BB918-DF28-46B3-94F7-144176841267\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.77\",\"matchCriteriaId\":\"B3D12E00-E42D-4056-B354-BAD4903C03A5\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.17\",\"matchCriteriaId\":\"A5E006E4-59C7-43C1-9231-62A72219F2BA\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.7\",\"matchCriteriaId\":\"69245D10-0B71-485E-80C3-A64F077004D3\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:6.0:-:*:*:*:*:*:*\",\"matchCriteriaId\":\"7BE551E5-89CF-47A8-9B26-03CE727FBA37\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"F666C8D8-6538-46D4-B318-87610DE64C34\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*\",\"matchCriteriaId\":\"58A9FEFF-C040-420D-8F0A-BFDAAA1DF258\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*\",\"matchCriteriaId\":\"1D2315C0-D46F-4F85-9754-F9E5E11374A6\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*\",\"matchCriteriaId\":\"512EE3A8-A590-4501-9A94-5D4B268D6138\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/4e8a0005d633a4adc98e3b65d5080f93b90d356b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/529e685e522b9d7fb379dbe6929dcdf520e34c8c\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/56145d237385ca0e7ca9ff7b226aaf2eb8ef368b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/9b02c5c4147f8af8ed783c8deb5df927a55c3951\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/cfcfa0ca0212162aa472551266038e8fd6768cff\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}"
  }
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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