PatchTheCVECVE-2026-118370: libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that
CVE-2026-118370 is a medium-severity flaw (CVSS 5.9) affecting affected software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document with a start tag carrying over 2^30 attributes to overflow attIndex and nPrefixes, crashing applications or corrupting heap memory.
Why this priority
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 5.9 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | High |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | n/a |
| CISA exploited list | No |
| Weakness | CWE-190 |
| Published | 2026-10-28 |
| Last modified | 2026-10-28 |
Last updated 2026-10-28 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Timeline
- Published CVE record published
- Updated Record last modified
Advisories and coverage
Research and news
- Vulners Bulletins: CVE-2026-118370 2026-10-28
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-118370?
No fixed release is listed yet. Watch the vendor advisory and apply any mitigation shown on this page.
Is CVE-2026-118370 being exploited?
CVE-2026-118370 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-118370 affect?
CVE-2026-118370 affects affected software. Severity is medium (CVSS 5.9). libexpat through 2.9.0 contains a signed integer overflow vulnerability in storeAtts() in lib/xmlparse.c that allows attackers to trigger out-of-bounds writes via oversized attribute counts. Attackers can supply a multi-gigabyte document wi
How urgent is CVE-2026-118370?
Priority 26/100. Remotely exploitable, no login, no user action