WebAssembly Binaryen Denial of Service Vulnerability in BrOn Parser
CVE-2026-8257

4.8MEDIUM

Key Information:

Vendor

Webassembly

Status
Binaryen
Vendor
CVE Published:
11 May 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-8257?

A vulnerability in WebAssembly Binaryen's BrOn Parser has been identified, which can lead to a Denial of Service condition. Specifically, the issue lies within the function IRBuilder::makeBrOn in the wasm-ir-builder.cpp file. Manipulation of this function could trigger a reachable assertion failure, potentially allowing local attackers to exploit the vulnerability. The issue is now publicly known, raising concerns about its exploitation. Users are advised to apply the patch (commit 1251efbc1ea471c1311d2726b2bbe061ff2a291c) to mitigate the risk.

Affected Version(s)

Binaryen 117

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-8257 - Proof of Concept

References

https://vuldb.com/vuln/362554
vdb-entrytechnical-description
https://vuldb.com/vuln/362554/cti
signaturepermissions-required
https://vuldb.com/submit/809552
third-party-advisory

CVSS V4

Score:
4.8
Severity:
MEDIUM
Confidentiality:
None
Integrity:
None
Availability:
Low
Attack Vector:
Local
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

pwn3rd (VulDB User)
.