What’s Vulnerable › Vulnerabilities

CVE-2026-50161: libre: Integer overflow in websock_decode() masked frame length check leads to heap buffer overflow

• Severity: critical (CVSS 9.3 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-18 · updated 2026-10-22
• Weakness: CWE-190

Description

libre is a generic library for real-time communications with asynchronous input and output support. Prior to 4.8.1, the websock_decode() function in src/websock/websock.c contains an integer overflow when validating a masked WebSocket frame that uses the 64-bit extended length encoding. The expression 4 + hdr->len can wrap when hdr->len is close to UINT64_MAX, causing the mbuf_get_left() bounds check to pass. The subsequent XOR unmasking loop then writes beyond the heap buffer. Applications using websock_accept() or websock_accept_proto() to implement a WebSocket server are affected, and exploitation can cause attacker-controlled heap corruption or denial of service after the HTTP WebSocket upgrade handshake. This issue is fixed in version 4.8.1.

Affected products

• baresip re: before 4.8.1

References

• https://github.com/baresip/re/commit/718b92615c7963670d26c1a2b246968b58d782e8
• https://github.com/baresip/re/pull/1584
• https://github.com/baresip/re/releases/tag/v4.8.1
• https://github.com/baresip/re/security/advisories/GHSA-hvxv-v2gp-v93h

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