Hexadecimal Conversion · Heap Buffer Overflow
Affects MicrosoftSource GCVE Database
Not known to be exploited · patch available : update Microsoft when convenient.
Data as of 30 Oct 2026, 06:59 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available
Exploitation evidence
Disclosed: evidence found.
CVE published 9 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 29 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Microsoft Security Response Center Microsoft | Affected
| Fixed in– |
AI-suggested
A fix is available and has been released in updated OpenSSL packages for Ubuntu 22.04 LTS, 24.04 LTS, 25.10, and related releases. Users should apply these updates and reboot their systems to ensure the vulnerability is remediated. No additional mitigation steps are required beyond applying the official patches.
Description
A heap buffer overflow vulnerability exists in OpenSSL on 32-bit platforms during hexadecimal conversion of large OCTET STRING values in X.509 certificates. This is caused by integer overflow in buffer size calculation when processing crafted certificates with large extensions like Subject Key Identifier or Authority Key Identifier. Exploitation could cause crashes or potentially allow attacker-controlled code execution, but requires certificates larger than 1 GB, making exploitation unlikely. The vulnerability does not affect OpenSSL FIPS modules. Fixes are available in updated OpenSSL packages for Ubuntu releases.
References
- msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-31789.json (opens in a new tab)
- support.microsoft.com/lifecycle (opens in a new tab)
- first.org/cvss (opens in a new tab)
- ubuntu.com/security/CVE-2026-31789 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-31789 (opens in a new tab)
- openwall.com/lists/oss-security/2026/04/07/11 (opens in a new tab)
- ubuntu.com/security/notices/USN-8155-1 (opens in a new tab)