TLSX_EchChangeSNI · Out-of-bounds Write
Affects MicrosoftSource GCVE Database
Not known to be exploited.
Data as of 27 Oct 2026, 00:12 UTC
Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Exploitation evidence
Disclosed: evidence found.
CVE published 2 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Security Response Center Microsoft | Affected
| Fixed in– |
AI-suggested
No official fixes or mitigation steps are currently documented. Users should monitor Microsoft Security Response Center advisories for updates.
Description
CVE-2026-5503 is a vulnerability in Microsoft products involving an out-of-bounds write triggered via the TLSX_EchChangeSNI function when processing an attacker-controlled publicName. This flaw is categorized under CWE-787, indicating a memory corruption issue. The affected versions explicitly include Microsoft product versions 2.0 and 3.0. No CVSS score is provided, and there is no indication of known exploitation in the wild. No patch or remediation details are currently available.