out-of-bounds write in TLSX_EchChangeSNI via attacker-controlled publicName_CVE-2026-5503

6.9 / 10

MEDIUM

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

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.

Basic Information

ID CVE-2026-5503

Source wolfSSL

Published Apr 9, 2026 at 22:35

Modified Apr 10, 2026 at 17:58

Affected Product

Vendor wolfSSL

Product wolfSSL

Affected Versions wolfSSL wolfSSL 0

CWE Classification

CWE-787

References

github.com /wolfSSL/wolfssl/pull/10102

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    "published": "2026-04-09T22:35:39.437Z",
    "modified": "2026-04-10T17:58:51.312Z",
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