CVE-2026-63383
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent can read beyond a contiguous evbuffer region in event_tagging.c when decode_tag_internal requests at most five bytes from evbuffer_pullup but iterates using the full logical buffer length. A fragmented evbuffer containing a six-byte malformed tag can therefore advance past the pullup window and trigger an out-of-bounds read, which can crash a process that decodes attacker-controlled tagged RPC data. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
CSIRTS triage
- What
- decode_tag_internal() performs out-of-bounds reads during tag decoding.
- Who is affected
- Libevent applications processing untrusted serialized tag data.
- Urgency
- High; out-of-bounds reads can leak memory or crash the application; prioritize patching.
- Action
- Update Libevent to a patched version; minimize processing of untrusted tag input.
AI-assisted analysis generated from the source advisory — verify against the original.
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Exploitation outlook
- Low exploitation risk0.38% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 32% of all EPSS-scored CVEs.
Advisory coverage (2)
External references
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