bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim (Linux Linux)
At a glance
- Source
- NVD
- EPSS
- EPSS 0.14 % · percentile 3 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- Linux
- NVD status
- Modified
Description
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.
Weaknesses (CWE)
- CWE-416 — Use After Free
References
- https://git.kernel.org/stable/c/529e685e522b9d7fb379dbe6929dcdf520e34c8c
- https://git.kernel.org/stable/c/9b02c5c4147f8af8ed783c8deb5df927a55c3951
- https://git.kernel.org/stable/c/cfcfa0ca0212162aa472551266038e8fd6768cff
- https://git.kernel.org/stable/c/3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2
- https://git.kernel.org/stable/c/4e8a0005d633a4adc98e3b65d5080f93b90d356b
- https://git.kernel.org/stable/c/56145d237385ca0e7ca9ff7b226aaf2eb8ef368b
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html
- https://cert-portal.siemens.com/productcert/html/ssa-784472.html
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H | NVD · nvd@nist.gov (Primary) |
European references
- ENISA EUVD · EUVD-2026-15269
- GCVE · GCVE-0-2026-23319
CERT-FR advisories
- CERTFR-2026-AVI-1298 — Multiples vulnérabilités dans les produits Siemens · cert.ssi.gouv.fr
- CERTFR-2026-AVI-1066 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0954 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0926 — Multiples vulnérabilités dans le noyau Linux d'Ubuntu · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0880 — Multiples vulnérabilités dans les produits Siemens · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0548 — Multiples vulnérabilités dans le noyau Linux de Debian · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0547 — Multiples vulnérabilités dans le noyau Linux de Debian LTS · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0546 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0497 — Multiples vulnérabilités dans le noyau Linux de SUSE · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0376 — Multiples vulnérabilités dans les produits Microsoft · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.0.1 < 6.1.167cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.2 < 6.6.130cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.7 < 6.12.77cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.13 < 6.18.17cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*≥ 6.19 < 6.19.7cpe:2.3:o:linux:linux_kernel:6.0:-:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*cpe:2.3:o:linux:linux_kernel:7.0:rc7:*:*:*:*:*:*
Affected products
| Product | Versions |
|---|---|
| Linux · Linux | affected 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 529e685e522b9d7fb379dbe6929dcdf520e34c8c ; affected 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 9b02c5c4147f8af8ed783c8deb5df927a55c3951 ; affected 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < cfcfa0ca0212162aa472551266038e8fd6768cff ; affected 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 3eeddb80191f7626ec1ef742bfff51ec3b0fa5c2 ; affected 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 4e8a0005d633a4adc98e3b65d5080f93b90d356b ; affected 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 56145d237385ca0e7ca9ff7b226aaf2eb8ef368b |
| Linux · Linux | affected 6.0 ; unaffected 0 < 6.0 ; unaffected 6.1.167 ≤ 6.1.* ; unaffected 6.6.130 ≤ 6.6.* ; unaffected 6.12.77 ≤ 6.12.* ; unaffected 6.18.17 ≤ 6.18.* |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |