CVE-2026-53262: Linux kernel · l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl()
Source GCVE Database
Not known to be exploited · CVSS 7.8 High · fixed in e251d4cdfc725c9e7d686161e3b775a0e7d95053 : patch Linux kernel soon.
Data as of 30 Oct 2026, 16:33 UTC
Thin evidence
One scorer or none| CNA (Linux) | CVSS 3.1 | 7.8 |
|---|
- Patch
- Available – fixed in e251d4cdfc725c9e7d686161e3b775a0e7d95053, cc19c164a99ab706d4cb45d3c300b305c16798b5, a213a8950414c684999dcf03edeea6c46ede172e +3
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
In the Linux kernel, the following vulnerability has been resolved: l2tp: pppol2tp: hold reference to session in pppol2tp_ioctl() pppol2tp_ioctl() read sock->sk->sk_user_data directly without any locks or reference counting. If a controllable sleep was induced during copy_from_user() (e.g. via a userfaultfd page fault sleep), a concurrent socket close could trigger pppol2tp_session_close() asynchronously. This frees the l2tp_session structure via the l2tp_session_del_work workqueue. Upon resuming, the ioctl thread dereferences the stale session pointer, resulting in a Use-After-Free (UAF). Fix this by securely fetching the session reference using the RCU-safe, refcounted helper pppol2tp_sock_to_session(sk) on entry. This locks the session's refcount across the sleep. We structured the function to exit via standard err breaks, guaranteeing that l2tp_session_put() is cleanly called on all return paths to drop the reference. To preserve existing behavior we validate the session and its magic signature only for the specific L2TP commands that require it. This ensures that generic/unknown ioctls called on an unconnected socket still return -ENOIOCTLCMD and correctly fall back to generic handlers (e.g. in sock_do_ioctl()).
References
- nvd.nist.gov/vuln/detail/CVE-2026-53262 (opens in a new tab)
- git.kernel.org/stable/c/312ecea13b67797747eb9d4b9dab8d3846de6dfb (opens in a new tab)
- git.kernel.org/stable/c/62f327e287cf7b595ae3f73ba72f5cd2a9e9f39f (opens in a new tab)
- git.kernel.org/stable/c/78cdfdca88cbf731a92f3b9ee5427c633dd94e28 (opens in a new tab)
- git.kernel.org/stable/c/a213a8950414c684999dcf03edeea6c46ede172e (opens in a new tab)
- git.kernel.org/stable/c/cc19c164a99ab706d4cb45d3c300b305c16798b5 (opens in a new tab)
- git.kernel.org/stable/c/e251d4cdfc725c9e7d686161e3b775a0e7d95053 (opens in a new tab)