Answer in brief
CVE-2024-49940 records a High severity (CVSS 7.8) vulnerability in l2tp: prevent possible tunnel refcount underflow. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=3953ae7b218df4d1e544b98a393666f9ae58a78c <f7415e60c25a6108cd7955a20b2e66b6251ffe02 || >=3953ae7b218df4d1e544b98a393666f9ae58a78c <24256415d18695b46da06c93135f5b51c548b950 || b102bfc2a90d14f342580285782a9a51c74f7369 || 10c15ddabbcf888922adbdd44ca3fecf6eab19d9 || 8d1c650d452c53fcb3f02a7b1d772741639f89a4 || 12b5fb58ac993c24210cf8cbc72d407d3a4e6490 || aef37401b467a0b1a9517c69924a1d66937e0789 || >=3.2.99 <3.3 || >=3.16.54 <3.17 || >=4.4.225 <4.5 || >=4.9.225 <4.10 || >=4.14.182 <4.15 | f7415e60c25a6108cd7955a20b2e66b6251ffe02, 24256415d18695b46da06c93135f5b51c548b950, 3.3, 3.17, 4.5, 4.10, 4.15 |
| Linux/Linuxgeneric | 4.15 | Not reported |
| Linux/Linuxgeneric | >=3953ae7b218df4d1e544b98a393666f9ae58a78c <98691b2e28a6c3dac0680914493d54c77f215755 || >=3953ae7b218df4d1e544b98a393666f9ae58a78c <f7415e60c25a6108cd7955a20b2e66b6251ffe02 || >=3953ae7b218df4d1e544b98a393666f9ae58a78c <24256415d18695b46da06c93135f5b51c548b950 || b102bfc2a90d14f342580285782a9a51c74f7369 || 10c15ddabbcf888922adbdd44ca3fecf6eab19d9 || 8d1c650d452c53fcb3f02a7b1d772741639f89a4 || 12b5fb58ac993c24210cf8cbc72d407d3a4e6490 || aef37401b467a0b1a9517c69924a1d66937e0789 || >=3.2.99 <3.3 || >=3.16.54 <3.17 || >=4.4.225 <4.5 || >=4.9.225 <4.10 || >=4.14.182 <4.15 | 98691b2e28a6c3dac0680914493d54c77f215755, f7415e60c25a6108cd7955a20b2e66b6251ffe02, 24256415d18695b46da06c93135f5b51c548b950, 3.3, 3.17, 4.5, 4.10, 4.15 |
| Linux/Linuxgeneric | >=3953ae7b218df4d1e544b98a393666f9ae58a78c <aa7132362e79abc4f2add4d8657dd1679341edc5 || >=3953ae7b218df4d1e544b98a393666f9ae58a78c <98691b2e28a6c3dac0680914493d54c77f215755 || >=3953ae7b218df4d1e544b98a393666f9ae58a78c <f7415e60c25a6108cd7955a20b2e66b6251ffe02 || >=3953ae7b218df4d1e544b98a393666f9ae58a78c <24256415d18695b46da06c93135f5b51c548b950 || b102bfc2a90d14f342580285782a9a51c74f7369 || 10c15ddabbcf888922adbdd44ca3fecf6eab19d9 || 8d1c650d452c53fcb3f02a7b1d772741639f89a4 || 12b5fb58ac993c24210cf8cbc72d407d3a4e6490 || aef37401b467a0b1a9517c69924a1d66937e0789 || >=3.2.99 <3.3 || >=3.16.54 <3.17 || >=4.4.225 <4.5 || >=4.9.225 <4.10 || >=4.14.182 <4.15 | aa7132362e79abc4f2add4d8657dd1679341edc5, 98691b2e28a6c3dac0680914493d54c77f215755, f7415e60c25a6108cd7955a20b2e66b6251ffe02, 24256415d18695b46da06c93135f5b51c548b950, 3.3, 3.17, 4.5, 4.10, 4.15 |
Published upstream
Oct 21, 2024
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 5, 2026
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.
Quoted source text, attributed separately from HOL analysis.