CVE-2026-34877

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-04-02. CISA-ADP (Vulnrichment) CVSS v3.1 baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: cisa-adp, epss, ghsa
Trending — 3 sources updated this week
9.8
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.8Exploit: NoneExposed: 0

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

An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused by Incorrect Use of Privileged APIs.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
59(Track)
EG Risk 59/100SSVC: 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
Severity98% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
34.9%
KEV
Not listed

Published

April 2, 2026

Last Modified

June 5, 2026

Advisory Details (2)

Auto-updated Jun 20, 2026
No patch confirmed yet.
generic

Risk of insufficient protection of serialized session or context data leading to potential memory safety issues (CVE-2026-34877) — Mbed TLS documentation

https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2026-03-serialized-data/
generic

Security Advisories — Mbed TLS documentation

https://mbed-tls.readthedocs.io/en/latest/security-advisories/

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 40× 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 116 total refreshes for this CVE.

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

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Frequently asked(5)

What is CVE-2026-34877?
CVE-2026-34877 is a critical vulnerability published on April 2, 2026. An issue was discovered in Mbed TLS versions from 2.19.0 up to 3.6.5, Mbed TLS 4.0.0. Insufficient protection of serialized SSL context or session structures allows an attacker who can modify the serialized structures to induce memory corruption, leading to arbitrary code execution. This is caused…
When was CVE-2026-34877 disclosed?
CVE-2026-34877 was first published in the National Vulnerability Database on April 2, 2026, with the most recent update on June 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-34877 actively exploited?
CVE-2026-34877 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-34877?
CVE-2026-34877 has a CVSS v3.1 base score of 9.8 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-34877?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-34877, 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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