CVE-2026-5503

CRITICALNVD 9.19.1—
EchelonGraph scoreMEDIUM confidence

Score 9.1 from GitHub Security Advisory published 2026-04-10. NVD baseline CVSS 9.1; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
9.1EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 9.1Exploit: None knownExposed: 0

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

In TLSX_EchChangeSNI, the ctx->extensions branch set extensions unconditionally even when TLSX_Find returned NULL. This caused TLSX_UseSNI to attach the attacker-controlled publicName to the shared WOLFSSL_CTX when no inner SNI was configured. TLSX_EchRestoreSNI then failed to clean it up because its removal was gated on serverNameX != NULL. The inner ClientHello was sized before the pollution but written after it, causing TLSX_SNI_Write to memcpy 255 bytes past the allocation boundary.

CVSS v3
9.1
EG Score
9.1(medium)
EG Risk
56(Track)
EG Risk 56/100SSVC: 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
Severity91% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
33%
KEV
Not listed

Published

April 9, 2026

Last Modified

April 27, 2026

Advisory Details (1)

Auto-updated Aug 1, 2026
Upstream fix merged — awaiting tagged release. Sources: github_pr.
github_pr

Various fixes

Fix merged in wolfSSL/wolfssl PR #10102 on 2026-04-06 — awaiting tagged release

https://github.com/wolfSSL/wolfssl/pull/10102

Vendor Advisories for CVE-2026-5503(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(3 across 3 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
wolfssl4.6.0+p1-0+deb11u1 ... 5.9.2-1 (40 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
wolfssl5.5.4-2 ... 5.9.2-1 (27 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
wolfssl5.7.2-0.1 ... 5.9.2-1 (14 versions)——

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 5× in last 7d / 26× 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 221 total refreshes for this CVE.

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

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-5503?
CVE-2026-5503 is a critical vulnerability published on April 9, 2026. In TLSXEchChangeSNI, the ctx->extensions branch set extensions unconditionally even when TLSXFind returned NULL. This caused TLSXUseSNI to attach the attacker-controlled publicName to the shared WOLFSSLCTX when no inner SNI was configured. TLSXEchRestoreSNI then failed to clean it up because its…
When was CVE-2026-5503 disclosed?
CVE-2026-5503 was first published in the National Vulnerability Database on April 9, 2026, with the most recent update on April 27, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-5503 actively exploited?
CVE-2026-5503 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 67.1% of all scored CVEs.
What is the CVSS score of CVE-2026-5503?
CVE-2026-5503 has a CVSS v3 base score of 9.1 (NVD).
How do I remediate CVE-2026-5503?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-5503, 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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