CVE-2026-63380
Libevent: Null Pointer Dereference in `evws_new_session`
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- High
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
5.7
Libevent: Null Pointer Dereference in `evws_new_session`
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
- Record
CVE-2026-63380- CVSS 4.0
- 5.7 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-416, CWE-476
- Updated
- 2026-11-02
EUVDEUVD-2026-63506
5.7
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
- Record
EUVD-2026-63506- CVSS 4.0
- 5.7 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
NVD
5.7
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
- Record
CVE-2026-63380- CVSS 4.0
- 5.7 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-416, CWE-476
- Updated
- 2026-11-02
OSV
5.7
Libevent: Null Pointer Dereference in `evws_new_session`
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
- Record
CVE-2026-63380- CVSS 4.0
- 5.7 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Weakness
- CWE-416, CWE-476
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-63380
5.7
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
- Record
UBUNTU-CVE-2026-63380- CVSS 4.0
- 5.7 Medium
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N - Updated
- 2026-11-02
OSVAZL-96912 No score
CVE-2026-63380 affecting package libtevent 0.14.1-1
Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.
- Record
AZL-96912- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
libteventAzure Linux:3 |
through 0.14.1-1 | None known |
libeventUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 2.0.21-stable-12.0.21-stable-1ubuntu12.0.21-stable-1ubuntu1.14.04.12.0.21-stable-1ubuntu1.14.04.22.0.21-stable-1ubuntu1.14.04.2+esm12.0.21-stable-1ubuntu1.14.04.2+esm2 |
None known |
libeventUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 2.0.21-stable-22.0.21-stable-2ubuntu0.16.04.12.0.21-stable-2ubuntu0.16.04.1+esm12.0.21-stable-2ubuntu0.16.04.1+esm2 |
None known |
libeventUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 2.1.8-stable-42.1.8-stable-4build12.1.8-stable-4ubuntu0.1~esm12.1.8-stable-4ubuntu0.1~esm2 |
None known |
libeventUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 2.1.8-stable-4build12.1.11-stable-1~exp02.1.11-stable-12.1.11-stable-1ubuntu0.1~esm12.1.11-stable-1ubuntu0.1~esm2 |
None known |
libeventUbuntu:22.04:LTS |
All versions, plus listed versions 2.1.12-stable-12.1.12-stable-1build12.1.12-stable-1build22.1.12-stable-1build32.1.12-stable-1ubuntu0.12.1.12-stable-1ubuntu0.2 |
None known |
libeventUbuntu:24.04:LTS |
All versions, plus listed versions 2.1.12-stable-92.1.12-stable-9ubuntu22.1.12-stable-9ubuntu2.12.1.12-stable-9ubuntu2.2 |
None known |
libeventUbuntu:26.10 |
All versions, plus listed versions 2.1.12-stable-10build22.1.13-stable-1build1 |
None known |
libeventUbuntu:26.04:LTS |
All versions, plus listed versions 2.1.12-stable-10build12.1.12-stable-10build22.1.12-stable-10ubuntu0.12.1.12-stable-10ubuntu0.2 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-63380 is a medium vulnerability (CVSS 5.7) in Libevent, published August 20, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.14%, the 3rd percentile. No source names a fixed version.
References
github.com/libevent/libevent/security/advisories/GHSA-3rpf-frgx-xq34
github.com/libevent/libevent/commit/825c18bd99f556b59d61200523237f264d5cc734
github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
nvd.nist.gov/vuln/detail/CVE-2026-63380
github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63380.json
ubuntu.com/security/CVE-2026-63380
cve.org/CVERecord?id=CVE-2026-63380