DEBIAN-CVE-2026-19953
- Source
- https://security-tracker.debian.org/tracker/CVE-2026-19953
- Import Source
- https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-19953.json
- JSON Data
- https://api.osv.dev/v1/vulns/DEBIAN-CVE-2026-19953
- Upstream
- Published
- 2026-08-31T18:17:14Z
- Modified
- 2026-09-14T17:02:39Z
- Severity
-
- 6.5 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N CVSS Calculator
- Summary
- [none]
- Details
-
URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep. nameprep lowercases each host label but performs no Unicode normalization. IDNA requires a label to be normalized to Form C before it is encoded (RFC 5891), so a label that is not already in NFC is encoded to a different A-label than its normalized form. A label built from the precomposed Devanagari sequence U+0958 U+093E encodes to xn--72b5c without normalization but to xn--11b2fg after NFC normalization, and xn--72b5c does not round-trip back to the original label. Any caller that reads host() from a URI built from untrusted input and uses it for a security decision (an allow or deny list, an SSRF filter, deduplication, a cache key) sees the non-standard label, while a client that fetches the same URL resolves the NFC form, so the check and the fetch can disagree about the host.
- References
Affected packages
Debian:12 / liburi-perl
Package
- Name
- liburi-perl
- Purl
- pkg:deb/debian/liburi-perl?arch=source&distro=bookworm
Affected ranges
- Type
- ECOSYSTEM
- Events
-
Introduced0 Unknown introduced version / All previous versions are affected
Debian:13 / liburi-perl
Package
- Name
- liburi-perl
- Purl
- pkg:deb/debian/liburi-perl?arch=source&distro=trixie
Debian:14 / liburi-perl
Package
- Name
- liburi-perl
- Purl
- pkg:deb/debian/liburi-perl?arch=source&distro=forky