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Description

A vulnerability was detected in WebAssembly Binaryen up to 117. This issue affects the function IRBuilder::makeBrOn of the file src/wasm/wasm-ir-builder.cpp of the component BrOn Parser. Performing a manipulation results in reachable assertion. The attack needs to be approached locally. The exploit is now public and may be used. The patch is named 1251efbc1ea471c1311d2726b2bbe061ff2a291c. It is suggested to install a patch to address this issue.

PUBLISHED Reserved 2026-05-10 | Published 2026-05-11 | Updated 2026-05-11 | Assigner VulDB




MEDIUM: 4.8CVSS: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
LOW: 3.3CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
LOW: 3.3CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
1.7AV:L/AC:L/Au:S/C:N/I:N/A:P/E:POC/RL:OF/RC:C

Problem types

Reachable Assertion

Product status

117
affected

Timeline

2026-05-10:Advisory disclosed
2026-05-10:VulDB entry created
2026-05-10:VulDB entry last update

Credits

pwn3rd (VulDB User) reporter

References

vuldb.com/vuln/362554 (VDB-362554 | WebAssembly Binaryen BrOn wasm-ir-builder.cpp makeBrOn assertion) vdb-entry technical-description

vuldb.com/vuln/362554/cti (VDB-362554 | CTI Indicators (IOB, IOC, IOA)) signature permissions-required

vuldb.com/submit/809552 (Submit #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)) third-party-advisory

github.com/WebAssembly/binaryen/issues/8633 issue-tracking

github.com/WebAssembly/binaryen/pull/8635 issue-tracking patch

github.com/...ure_isRef_wasm_Type_getHeapType_commit_3ef8d19 exploit patch

github.com/...ommit/1251efbc1ea471c1311d2726b2bbe061ff2a291c patch

github.com/WebAssembly/binaryen/ product

cve.org (CVE-2026-8257)

nvd.nist.gov (CVE-2026-8257)

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