CVE-2026-5503CRITICAL 9.1EPSS p27.3%
CVE-2026-5503CVE-2026-5503
Description
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.
Scoring
| CVSS 3.1 | 9.1 (CRITICAL) |
| Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H |
| EPSS | 0.36% probability of exploitation · percentile 27.3% · 2026-06-19T12:03:05Z |
| Published | 2026-04-09 |
| Last modified | 2026-04-27 |
Underlying weaknesses· 1
References
1
| Type | Target | Confidence | Tier |
|---|---|---|---|
| Weakness | Out-of-bounds Writecwe-787 | 0% | live |
Related by meaning· 6
Nearest entities by semantic similarity across the cs-graph corpus.