# CVE-2026-63384: Libevent integer overflow in evtag_unmarshal_header

Source: https://junglewise.ai/threats/cve-2026-63384-libevent-integer-overflow-in-evtag-unmarshal-header  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-20. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-63384 · Severity: info · CVSS 7.5 · Published 2026-08-20

Libevent is a widely-used event notification library that powers many network applications. A flaw in its RPC tagging component allows an attacker to send a specially-crafted message that triggers incorrect memory allocation, leading to crashes or denial of service of applications using vulnerable versions of the library.

Technologies: [Libevent](https://junglewise.ai/threats/technologies/libevent). Vendors: [Libevent](https://junglewise.ai/threats/vendors/libevent).

## Quick answers

**Is CVE-2026-63384 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-63384 being exploited in the wild.

**How severe is CVE-2026-63384?** Informational severity, with a CVSS score of 7.5, published 20 August 2026.

**Which products and versions are affected?** Libevent before 2.1.13 and before 2.2.2-alpha.

**Is there a fix for CVE-2026-63384?** A patch was published on 2026-08-20: Patches available 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-2026-63384 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-63384?** 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 an integer conversion flaw in event_tagging.c, specifically in the evtag_unmarshal_header function. When decoding an attacker-controlled uint32 payload length via evtag_decode_int, values exceeding INT_MAX are incorrectly converted to negative or truncated values when cast to a signed int. This malformed length is then passed to evtag_unmarshal_string for memory allocation sizing, causing a wrapped/oversized allocation request that results in denial of service. The fix rejects any payload length larger than INT_MAX. No authentication or special privileges are required; an attacker only needs network access to send a malicious RPC message to an application using vulnerable libevent versions (before 2.1.13 or 2.2.2-alpha).

## Affected products

- Libevent Libevent before 2.1.13 and before 2.2.2-alpha

## Timeline

- 2026-08-20: disclosed: CVE-2026-63384 published
- 2026-08-20: patched: Patches available in versions 2.1.13 and 2.2.2-alpha

## References

- [https://github.com/libevent/libevent/commit/109c16499282959d70f56ec3baf4c8b1e6646bda](https://github.com/libevent/libevent/commit/109c16499282959d70f56ec3baf4c8b1e6646bda)
- [https://github.com/libevent/libevent/commit/5e3c6ebe342b34c5a9bcf48e9a32ad6708b9c416](https://github.com/libevent/libevent/commit/5e3c6ebe342b34c5a9bcf48e9a32ad6708b9c416)

## Related threats

- [Libevent WebSocket unbounded memory accumulation via frame fragmentation](https://junglewise.ai/threats/cve-2026-63495-libevent-websocket-unbounded-memory-accumulation-via-frame)
- [Libevent heap out-of-bounds write in bufferevent_sock](https://junglewise.ai/threats/cve-2026-63388-libevent-heap-out-of-bounds-write-in-bufferevent-sock)
- [Libevent off-by-one stack buffer overflow in DNS response parsing](https://junglewise.ai/threats/cve-2026-63387-libevent-off-by-one-stack-buffer-overflow-in-dns-response-parsing)
- [Libevent out-of-bounds read in event_tagging](https://junglewise.ai/threats/cve-2026-63383-libevent-out-of-bounds-read-in-event-tagging)
- [Libevent HTTP request smuggling via inconsistent Transfer-Encoding parsing](https://junglewise.ai/threats/cve-2026-63382-libevent-http-request-smuggling-via-inconsistent-transfer)