CVE-2026-8257

Exploitation

Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.

SSVC decision

• ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
• AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
• Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.16% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 5.6% of scored records. A rank, not a probability.

NVD base score

1.9 (CVSS v4.0), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P/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

NVD analysis status

Analyzed. NVD last modified this record on 2026-07-23.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2026-05-11 00:30Z3 MO AGO

Last updated

2026-05-11 17:31Z3 MO AGO

Reserved

2026-05-10

Assigning CNA

VulDB

Record state

PUBLISHED

Severity

Medium (CVSS 4.8)

CNA CVSS vector

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P

Weaknesses

• CWE-617Reachable AssertionBase

Data version

5.2

Document digest

8171ab802ae7bc8fc2e9a8e74bb6aa649675bd25e9f3b5926186cbf17a1ec453

• vuldb.comVDB-362554 | WebAssembly Binaryen BrOn wasm-ir-builder.cpp makeBrOn assertionhttps://vuldb.com/vuln/362554vdb-entrytechnical-description
• vuldb.comVDB-362554 | CTI Indicators (IOB, IOC, IOA)https://vuldb.com/vuln/362554/ctisignaturepermissions-required
• vuldb.comSubmit #809552 | WebAssembly Community Binaryen main branch commit 3ef8d19 (v117 development version, vulnerable version before fix commit 1251efb) Fixed version: commit 1251ef Assertion Failure, Denial of Service (Local DoS)https://vuldb.com/submit/809552third-party-advisory
• github.comhttps://github.com/WebAssembly/binaryen/issues/8633issue-tracking
• github.comhttps://github.com/WebAssembly/binaryen/pull/8635issue-trackingpatch
• github.comhttps://github.com/HackC0der/CVE-Repos/blob/main/wasm-binaryen/Assertion_Failure_isRef_wasm_Type_getHeapType_commit_3ef8d19exploitpatch
• github.comhttps://github.com/WebAssembly/binaryen/commit/1251efbc1ea471c1311d2726b2bbe061ff2a291cpatch
• github.comhttps://github.com/WebAssembly/binaryen/product