CVE-2024-49940l2tp: prevent possible tunnel refcount underflow
Updated under an hour ago ()
Does this affect you?
It affects Linux and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
Do this next
Free account, 1 product
In the Linux kernel, the following vulnerability has been resolved: l2tp: prevent possible tunnel refcount underflow When a session is created, it sets a backpointer to its tunnel. When the session refcount drops to 0, l2tp_session_free drops the tunnel refcount if session->tunnel is non-NULL. However, session->tunnel is set in l2tp_session_create, before the tunnel refcount is incremented by l2tp_session_register, which leaves a small window where session->tunnel is non-NULL when the tunnel refcount hasn't been bumped. Moving the assignment to l2tp_session_register is trivial but l2tp_session_create calls l2tp_session_set_header_len which uses session->tunnel to get the tunnel's encap. Add an encap arg to l2tp_session_set_header_len to avoid using session->tunnel. If l2tpv3 sessions have colliding IDs, it is possible for l2tp_v3_session_get to race with l2tp_session_register and fetch a session which doesn't yet have session->tunnel set. Add a check for this case.
- CVSS
- 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 21, 2026
- First seen by InfoSec Signals
- Oct 21, 2026
Affected products
Linux Linux linux:linux (from the name) | from 3953ae7b218df4d1e544b98a393666f9ae58a78c before 98691b2e28a6c3dac0680914493d54c77f215755; from 3953ae7b218df4d1e544b98a393666f9ae58a78c before f7415e60c25a6108cd7955a20b2e66b6251ffe02; from 3953ae7b218df4d1e544b98a393666f9ae58a78c before 24256415d18695b46da06c93135f5b51c548b950; b102bfc2a90d14f342580285782a9a51c74f7369; 10c15ddabbcf888922adbdd44ca3fecf6eab19d9; 8d1c650d452c53fcb3f02a7b1d772741639f89a4; 12b5fb58ac993c24210cf8cbc72d407d3a4e6490; aef37401b467a0b1a9517c69924a1d66937e0789; and 5 more ranges | CNA record |
linux linux_kernel linux:linux_kernel | before 6.11.3 | NVD |
References
- https://git.kernel.org/stable/c/98691b2e28a6c3dac0680914493d54c77f215755
- https://git.kernel.org/stable/c/f7415e60c25a6108cd7955a20b2e66b6251ffe02patch
- https://git.kernel.org/stable/c/24256415d18695b46da06c93135f5b51c548b950patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.