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URL: https://nvd.nist.gov/vuln/detail/CVE-2026-5503

⇱ NVD - CVE-2026-5503

  1. Vulnerabilities

CVE-2026-5503 Detail

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.


Metrics

 
NVD enrichment efforts reference publicly available information to associate vector strings. CVSS information contributed by other sources is also displayed.
CVSS 4.0 Severity and Vector Strings:

NVD assessment not yet provided.

CVSS-B 6.9 MEDIUM
Vector:  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

References to Advisories, Solutions, and Tools

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URL Source(s) Tag(s)
https://github.com/wolfSSL/wolfssl/pull/10102 wolfSSL Inc. Issue Tracking 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-787 Out-of-bounds Write wolfSSL Inc.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

4 change records found show changes

CVE Modified by CISA-ADP 6/17/2026 6:59:08 AM

Action Type Old Value New Value
Added SSVC 
{"timestamp":"2026-04-10T17:58:43.475862Z","id":"CVE-2026-5503","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

CVE Modified by wolfSSL Inc. 6/17/2026 6:59:08 AM

Action Type Old Value New Value
Added Affected 
[{"vendor":"wolfSSL","product":"wolfSSL","defaultStatus":"unaffected","versions":[{"version":"0","lessThanOrEqual":"5.9.0","versionType":"semver","status":"affected"}]}]

Initial Analysis by NIST 4/27/2026 1:53:27 PM

Action Type Old Value New Value
Added CVSS V3.1 
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Added CPE Configuration 
OR
 *cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:* versions up to (including) 5.9.0
Added Reference Type 
wolfSSL Inc.: https://github.com/wolfSSL/wolfssl/pull/10102 Types: Issue Tracking

New CVE Received from wolfSSL Inc. 4/09/2026 7:17:01 PM

Action Type Old Value New Value
Added 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.
Added CVSS V4.0 
AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Added CWE 
CWE-787
Added Reference 
https://github.com/wolfSSL/wolfssl/pull/10102

Quick Info

CVE Dictionary Entry:
CVE-2026-5503
NVD Published Date:
04/09/2026
NVD Last Modified:
06/17/2026
Source:
wolfSSL Inc.