CVE-2026-8257

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.5 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 94% of all CVEs by exploit prediction. GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
Elevated
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: Elevated riskExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation40% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
5%
KEV
Not listed

Published

May 11, 2026

Last Modified

July 23, 2026

Advisory Details (5)

Auto-updated Jul 25, 2026
Upstream fix merged — awaiting tagged release. Sources: github_commit, github_pr.
github_pr

Avoid assertion in BrOn parsing

Fix merged in WebAssembly/binaryen PR #8635 on 2026-04-21 — awaiting tagged release

https://github.com/WebAssembly/binaryen/pull/8635
generic

Assertion failure isRef() in wasm::Type::getHeapType() at wasm-type.h:407 (main branch @3ef8d19) · Issue #8633 · WebAssembly/binaryen · GitHub

https://github.com/WebAssembly/binaryen/issues/8633
github_commit

commit 1251efbc1ea4 (WebAssembly/binaryen)

Fix landed in WebAssembly/binaryen commit 1251efbc1ea4 — awaiting tagged release

https://github.com/WebAssembly/binaryen/commit/1251efbc1ea471c1311d2726b2bbe061ff2a291c
generic

GitHub - WebAssembly/binaryen: Optimizer and compiler/toolchain library for WebAssembly · GitHub

https://github.com/WebAssembly/binaryen/
generic

CVE-Repos/wasm-binaryen/Assertion_Failure_isRef_wasm_Type_getHeapType_commit_3ef8d19 at main · HackC0der/CVE-Repos · GitHub

https://github.com/HackC0der/CVE-Repos/blob/main/wasm-binaryen/Assertion_Failure_isRef_wasm_Type_getHeapType_commit_3ef8d19

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
binaryen100-1 ... 99-3 (24 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
binaryen108-1 ... 131-2 (16 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
binaryen120-4 ... 131-2 (10 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
binaryen120-4 ... 131-2 (10 versions)——

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 5× in last 7d / 31× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 163 total refreshes for this CVE.

  1. 2026-09-15 03:12 UTCEPSS rescore
  2. 2026-09-13 16:48 UTCEPSS rescore
  3. 2026-09-12 15:02 UTCEPSS rescore
  4. 2026-09-11 12:23 UTCOSV refresh
  5. 2026-09-08 22:01 UTCEPSS rescore
  6. 2026-09-06 13:48 UTCEPSS rescore
  7. 2026-09-05 15:31 UTCEPSS rescore
  8. 2026-09-04 05:07 UTCEPSS rescore
  9. 2026-09-02 14:12 UTCEPSS rescore
  10. 2026-09-01 13:54 UTCEPSS rescore
  11. 2026-09-01 04:40 UTCEPSS rescore
  12. 2026-08-30 19:18 UTCEPSS rescore
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  14. 2026-08-30 01:22 UTCEPSS rescore
  15. 2026-08-28 21:42 UTCEPSS rescore
  16. 2026-08-27 14:25 UTCEPSS rescore
  17. 2026-08-26 14:47 UTCEPSS rescore
  18. 2026-08-25 13:49 UTCEPSS rescore
  19. 2026-08-24 14:18 UTCEPSS rescore
  20. 2026-08-23 18:44 UTCEG score recompute
  21. 2026-08-23 18:44 UTCGHSA enrichment
  22. 2026-08-21 23:49 UTCEPSS rescore
  23. 2026-08-20 22:56 UTCEPSS rescore
  24. 2026-08-19 17:04 UTCEPSS rescore
  25. 2026-08-18 13:49 UTCEPSS rescore
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  1. 2026-08-18 13:49 UTCEPSS rescore
  2. 2026-08-17 13:47 UTCEPSS rescore
  3. 2026-08-17 11:19 UTCEG score recompute
  4. 2026-08-17 11:19 UTCGHSA enrichment
  5. 2026-08-16 14:56 UTCEPSS rescore
  6. 2026-08-16 14:56 UTCEPSS rescore
  7. 2026-08-16 04:28 UTCEG score recompute
  8. 2026-08-16 04:28 UTCGHSA enrichment
  9. 2026-08-16 02:15 UTCEPSS rescore
  10. 2026-08-15 01:31 UTCEPSS rescore
  11. 2026-08-14 03:02 UTCEG score recompute
  12. 2026-08-14 03:02 UTCGHSA enrichment
  13. 2026-08-13 22:00 UTCEPSS rescore
  14. 2026-08-13 01:38 UTCEG score recompute
  15. 2026-08-13 01:38 UTCGHSA enrichment
  16. 2026-08-12 13:51 UTCEPSS rescore
  17. 2026-08-12 01:48 UTCGHSA enrichment
  18. 2026-08-11 01:58 UTCEG score recompute
  19. 2026-08-11 01:58 UTCGHSA enrichment
  20. 2026-08-11 00:00 UTCEPSS rescore
  21. 2026-08-10 02:08 UTCEG score recompute
  22. 2026-08-10 02:08 UTCGHSA enrichment
  23. 2026-08-09 13:47 UTCEPSS rescore
  24. 2026-08-09 02:18 UTCEG score recompute
  25. 2026-08-09 02:18 UTCGHSA enrichment
  26. 2026-08-08 16:37 UTCEPSS rescore
  27. 2026-08-08 01:29 UTCEG score recompute
  28. 2026-08-08 01:29 UTCGHSA enrichment
  29. 2026-08-07 01:39 UTCEG score recompute
  30. 2026-08-07 01:39 UTCGHSA enrichment
  31. 2026-08-06 13:47 UTCEPSS rescore
  32. 2026-08-05 22:00 UTCEG score recompute
  33. 2026-08-05 22:00 UTCGHSA enrichment
  34. 2026-08-05 19:17 UTCEPSS rescore
  35. 2026-08-05 19:17 UTCEPSS rescore
  36. 2026-08-04 15:10 UTCEPSS rescore
  37. 2026-08-04 10:39 UTCEPSS rescore
  38. 2026-08-04 02:02 UTCEG score recompute
  39. 2026-08-04 02:01 UTCGHSA enrichment
  40. 2026-08-03 10:36 UTCEPSS rescore
  41. 2026-08-03 02:11 UTCEG score recompute
  42. 2026-08-03 02:11 UTCGHSA enrichment
  43. 2026-08-02 02:27 UTCEPSS rescore
  44. 2026-08-02 02:20 UTCEG score recompute
  45. 2026-08-02 02:20 UTCGHSA enrichment
  46. 2026-08-01 04:16 UTCEPSS rescore
  47. 2026-07-30 16:28 UTCEPSS rescore
  48. 2026-07-30 01:30 UTCEPSS rescore
  49. 2026-07-28 15:37 UTCEPSS rescore
  50. 2026-07-27 14:14 UTCEPSS rescore
  51. 2026-07-26 14:54 UTCEPSS rescore
  52. 2026-07-26 08:23 UTCEG score recompute▲ 2.20
  53. 2026-07-26 08:23 UTCGHSA enrichment
  54. 2026-07-25 14:18 UTCEPSS rescore
  55. 2026-07-24 14:18 UTCEPSS rescore
  56. 2026-07-23 20:11 UTCNVD updateCVSS v3 → 5.5 · CVSS v4 → 1.9 · severity → MEDIUM
  57. 2026-07-23 14:18 UTCEPSS rescore
  58. 2026-07-23 03:23 UTCEG score recompute
  59. 2026-07-22 14:08 UTCEPSS rescore
  60. 2026-07-21 15:25 UTCEPSS rescore
  61. 2026-07-21 15:25 UTCEPSS rescore
  62. 2026-07-20 17:08 UTCEPSS rescore
  63. 2026-07-19 14:31 UTCEPSS rescore
  64. 2026-07-19 02:29 UTCEPSS rescore
  65. 2026-07-16 17:03 UTCEPSS rescore
  66. 2026-07-15 16:57 UTCEPSS rescore
  67. 2026-07-15 02:00 UTCEPSS rescore
  68. 2026-07-14 07:55 UTCOSV refresh
  69. 2026-07-13 22:31 UTCEPSS rescore
  70. 2026-07-13 06:13 UTCEPSS rescore
  71. 2026-07-12 05:46 UTCEPSS rescore
  72. 2026-07-11 08:27 UTCEPSS rescore
  73. 2026-07-09 19:10 UTCEPSS rescore
  74. 2026-07-08 15:16 UTCEPSS rescore
  75. 2026-07-08 15:16 UTCEPSS rescore

Frequently asked(5)

What is CVE-2026-8257?
CVE-2026-8257 is a medium vulnerability published on May 11, 2026. 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…
When was CVE-2026-8257 disclosed?
CVE-2026-8257 was first published in the National Vulnerability Database on May 11, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-8257 actively exploited?
CVE-2026-8257 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 94.6% of all scored CVEs.
What is the CVSS score of CVE-2026-8257?
CVE-2026-8257 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-8257?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-8257, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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