Off-by-one in yauzl - CVE-2026-31988
Published: April 22, 2026
Vulnerability identifier: #VU126854
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-31988
CWE-ID: CWE-193
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: thejoshwolfe
Affected software:
yauzl
yauzl
Detailed vulnerability description
The vulnerability allows a remote attacker to perform a denial of service attack.
The vulnerability exists due to an off-by-one error in the NTFS extended timestamp extra field parser within the getLastModDate() function. The while loop condition checks cursor < data.length + 4 instead of cursor + 4 <= data.length, allowing readUInt16LE() to read past the buffer boundary. A remote attacker can cause a denial of service (process crash via ERR_OUT_OF_RANGE exception) by sending a crafted zip file with a malformed NTFS extra field.
How to mitigate CVE-2026-31988
Install updates from vendor's website.
Sources
- https://github.com/thejoshwolfe/yauzl/commit/c4695215b05c6adffda613b9051a2a85429b33fe
- https://www.codeant.ai/security-research/yauzl-denial-of-service-zip-file-crash
- https://www.npmjs.com/package/yauzl
- https://www.vulncheck.com/advisories/yauzl-denial-of-service-via-off-by-one-error-in-ntfs-timestamp-parser