CVE-2026-40257

MEDIUMPre-NVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1%, top 99% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

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

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

OP-TEE is a Trusted Execution Environment (TEE) designed as companion to a non-secure Linux kernel running on Arm; Cortex-A cores using the TrustZone technology. Starting in version 3.21.0 and prior to version 4.11.0, the ARM Crypto Extensions accelerated SHA-3 implementation has an off-by-one error that can cause a massive heap overflow that corrupts all TEE kernel memory following the hash state. This affects all platforms built with CFG_CRYPTO_WITH_CE82=y (ARMv8.2+ with SHA3 Crypto Extensions). Version 4.11.0 contains a patch. As a workaround, disable SHA3 Crypto Extensions with CFG_CRYPTO_WITH_CE82=n.

CVSS v3
5.5
EG Score
5.5(medium)
EPSS
1.5%
KEV
Not listed

Published

July 6, 2026

Last Modified

July 7, 2026

Advisory Details (1)

Auto-updated Jul 7, 2026
Patch available. Sources: github.
github Patch Available

SHA-3 accelerated finalize heap overflow · Advisory · OP-TEE/optee_os · GitHub

https://github.com/OP-TEE/optee_os/security/advisories/GHSA-75x4-j8p9-55qv

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 18× 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.

  1. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 16:57 UTCEPSS rescore
  3. 2026-07-15 03:02 UTCEG score recompute
  4. 2026-07-14 01:43 UTCEG score recompute
  5. 2026-07-13 22:30 UTCEPSS rescore
  6. 2026-07-13 00:27 UTCEG score recompute
  7. 2026-07-12 05:46 UTCEPSS rescore
  8. 2026-07-11 23:10 UTCEG score recompute
  9. 2026-07-11 08:27 UTCEPSS rescore
  10. 2026-07-10 21:52 UTCEG score recompute
  11. 2026-07-09 20:35 UTCEG score recompute
  12. 2026-07-09 19:10 UTCEPSS rescore
  13. 2026-07-08 19:17 UTCEG score recompute
  14. 2026-07-08 15:15 UTCEPSS rescore
  15. 2026-07-07 18:00 UTCEG score recompute
  16. 2026-07-07 13:46 UTCEPSS rescore
  17. 2026-07-06 16:43 UTCEG score recompute
  18. 2026-07-06 16:41 UTCMITRE cvelistV5first tracked

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Frequently asked(5)

What is CVE-2026-40257?
CVE-2026-40257 is a medium vulnerability published on July 6, 2026. OP-TEE is a Trusted Execution Environment (TEE) designed as companion to a non-secure Linux kernel running on Arm; Cortex-A cores using the TrustZone technology. Starting in version 3.21.0 and prior to version 4.11.0, the ARM Crypto Extensions accelerated SHA-3 implementation has an off-by-one…
When was CVE-2026-40257 disclosed?
CVE-2026-40257 was first published in the National Vulnerability Database on July 6, 2026, with the most recent update on July 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40257 actively exploited?
CVE-2026-40257 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40257?
CVE-2026-40257 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2026-40257?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40257, 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.

Dependency Blast Radius

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