01 Record

CVE-2026-19953

URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep

MediumPUBLISHEDCNA: CPANSec

CNA base score6.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

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02 Description

URI versions before 5.36 for Perl encode non-NFC host names to non-standard punycode labels via missing normalization in nameprep

03 Exploitation and scoring

Exploitation

Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.

SSVC decision

ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

0.22% probability of exploitation activity in the next 30 days.

EPSS percentile

Equal to or higher than the score of 13.6% of scored records. A rank, not a probability.

NVD base score

6.5 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

NVD analysis status

Deferred. NVD last modified this record on 2026-09-03.

Red Hat severity

Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published

2026-08-31 17:29Z1 MO AGO

Last updated

2026-09-01 15:16Z1 MO AGO

Reserved

2026-08-15

Assigning CNA

CPANSec

Record state

PUBLISHED

Severity

Medium (CVSS 6.5)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Weaknesses

CWE-1289Improper Validation of Unsafe Equivalence in InputBase
CWE-838Inappropriate Encoding for Output ContextBase

Data version

5.2

Document digest

8c93506bf239970fc75c8a88b303d776a7a2513822d425851b5388e52da8dcd4

05 Affected products

VendorProductVersionsPlatforms

redhatcost_management_on_premiseNot specified—

redhatenterprise_linuxNot specified—

redhathummingbirdNot specified—

redhatopenshiftNot specified—

06 References

github.comhttps://github.com/libwww-perl/URI/commit/956619a9e94f86d8d2c529b4e06a3674c54a73e7.patchpatch
github.comhttps://github.com/libwww-perl/URI/pull/191issue-tracking
metacpan.orghttps://metacpan.org/release/OALDERS/URI-5.36/changesrelease-notes
www.rfc-editor.orghttps://www.rfc-editor.org/rfc/rfc5891#section-5.2technical-description
www.openwall.comhttp://www.openwall.com/lists/oss-security/2026/08/31/14

07 Remediation

Upgrade to URI 5.36 or later.

08 Fixed in

AlmaLinux 8

perl-URI
Fixed in 1.73-4.el8_10

AlmaLinux 9

perl-URI
Fixed in 5.09-3.el9_8.1

AlmaLinux 10

perl-URI
Fixed in 5.27-3.el10_2.1

CloudLinux 8

perl-URI
Fixed in 1.73-4.el8_10

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

CloudLinux 9

perl-URI
Fixed in 5.09-3.el9_8.1

Derived from AlmaLinux 9. Partial coverage: only packages taken from AlmaLinux 9 are listed.

CloudLinux 10

perl-URI
Fixed in 5.27-3.el10_2.1

Derived from AlmaLinux 10. Partial coverage: only packages taken from AlmaLinux 10 are listed.

Debian 12

liburi-perl
No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

liburi-perl
No fix yet

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

liburi-perl
Fixed in 5.36-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.