CVE-2026-5503 Affecting wolfssl package, versions <5.9.1-r0


Severity

Recommended
0.0
critical
0
10

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Threat Intelligence

EPSS
0.05% (17th percentile)

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  • Snyk IDSNYK-ALPINE323-WOLFSSL-17037455
  • published29 May 2026
  • disclosed9 Apr 2026

Introduced: 9 Apr 2026

CVE-2026-5503  (opens in a new tab)

How to fix?

Upgrade Alpine:3.23 wolfssl to version 5.9.1-r0 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream wolfssl package and not the wolfssl package as distributed by Alpine. See How to fix? for Alpine:3.23 relevant fixed versions and status.

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 Base Scores

version 3.1