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libre CVE-2026-50161

| EUVDEUVD-2026-61137 CRITICAL
Integer Overflow or Wraparound (CWE-190)
2026-08-18 security-advisories@github.com
Integer Overflow Denial Of Service
9.3
CVSS 4.0 · Vendor: github
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Vendor (github) PRIMARY
9.3 CRITICAL
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/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
vuln.today AI
9.8 CRITICAL

Unauthenticated network-reachable frame after a public WebSocket handshake gives AV:N/AC:L/PR:N/UI:N; attacker-controlled heap corruption supports C/I/A:H with unchanged scope.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (github).

CVSS VectorVendor: github

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
Patch available
Aug 18, 2026 - 19:04 EUVD
Source Code Evidence Fetched
Aug 18, 2026 - 18:32 vuln.today
Analysis Generated
Aug 18, 2026 - 18:32 vuln.today
CVE Published
Aug 18, 2026 - 18:17 cve.org
CRITICAL 9.3

DescriptionCVE.org

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.

AnalysisAI

Heap buffer overflow in the baresip 'libre' real-time communications library (versions prior to 4.8.1) lets remote attackers corrupt heap memory or crash any application running a WebSocket server via websock_accept()/websock_accept_proto(). The websock_decode() function miscalculates frame bounds for 64-bit extended-length masked frames, and the out-of-bounds XOR unmasking write is attacker-controlled. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Vulnerability AssessmentAI

Exploitation Exploitation requires that the target application uses libre's WebSocket server functionality via websock_accept() or websock_accept_proto() and that the attacker can reach that endpoint and complete the HTTP WebSocket upgrade handshake. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment All primary signals point the same direction and are consistent: the CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:N/UI:N with VC:H/VI:H/VA:H, base 9.3 Critical) describes a network-reachable, low-complexity, unauthenticated flaw with high impact to confidentiality, integrity and availability, matching a description of attacker-controlled heap corruption or DoS reachable by any client that completes a WebSocket upgrade. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario Full exploit scenario with step-by-step reproduction available after sign-in.
Remediation Vendor-released patch: 4.8.1 - upgrade libre (baresip/re) to version 4.8.1 or later, which adds the 'hdr->len > SIZE_MAX - 4' overflow guard (commit 718b92615c7963670d26c1a2b246968b58d782e8, PR https://github.com/baresip/re/pull/1584, advisory https://github.com/baresip/re/security/advisories/GHSA-hvxv-v2gp-v93h, release https://github.com/baresip/re/releases/tag/v4.8.1); downstream projects that statically or dynamically link libre must rebuild against the patched library. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours: conduct a complete inventory of all applications and infrastructure using baresip libre and document current versions in production; determine which deployments expose WebSocket servers to untrusted networks. …

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Same weakness CWE-190 – Integer Overflow or Wraparound

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CVE-2026-50161 vulnerability details – vuln.today
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