Quick answers
- Is CVE-2026-63381 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-63381 being exploited in the wild.
- How severe is CVE-2026-63381?
- Informational severity, published 20 August 2026.
- Which products and versions are affected?
- Libevent before 2.1.13, before 2.2.2-alpha.
- Is there a fix for CVE-2026-63381?
- A patch was published on 2026-08-20: Fixed in versions 2.1.13 and 2.2.2-alpha Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-63381 attacked?
- It is attacked over the network or with local access.
- Am I affected by CVE-2026-63381?
- Check whether you run Libevent at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a use-after-free in buffer.c's evbuffer_add_buffer_reference function. When processing an output buffer with zero out_total_len, evbuffer_free_all_chains frees the initial empty chain but fails to reset the pointers outbuf->first, outbuf->last, and outbuf->last_with_datap, leaving dangling references. The APPEND_CHAIN_MULTICAST macro subsequently dereferences these dangling pointers, leading to memory corruption. An attacker who can drive this buffer state through application-specific APIs can trigger a crash or memory corruption. The issue is fixed in libevent 2.1.13 and 2.2.2-alpha.
Affected products
- Libevent libevent before 2.1.13, before 2.2.2-alpha
Timeline
- 2026-08-20: disclosed
- 2026-08-20: patched: Fixed in versions 2.1.13 and 2.2.2-alpha