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Fedora 43 Faces Significant Issue with IDNA Normalization in perl

Linuxsecurity •LinuxSecurity Advisories • August 25, 2026

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This module implements the URI class. Objects of this class represent

"Uniform Resource Identifier references" as specified in RFC 2396 (and

updated by RFC 2732).

5.36 - Apply Unicode NFC normalization in URI::_idna nameprep so IDNA host encoding matches other clients instead of emitting a non-standard, non-round- tripping A-label [CVE-2026-19953]

* Fri Aug 21 2026 Jitka Plesnikova - 5.36-1 - 5.36 bump (rhbz#2520744) - Fix CVE-2026-19953 (IDNA host encoding / Unicode NFC normalization)

[ 1 ] Bug #2520744 - perl-URI-5.36 is available

This update can be installed with the "dnf" update program. Use su -c 'dnf upgrade --advisory FEDORA-2026-09941e744b' at the command line. For more information, refer to the dnf documentation available at

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This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.

Fedora 43 and 44 Vulnerability in perl-URI IDNA Normalization Fedora 43 and 44 face a significant vulnerability related to IDNA normalization in the perl-URI module, identified as CVE-2026-19953. This issue affects the handling of Unicode NFC normalization, leading to potential discrepancies in IDNA host encoding. The vulnerability was patched on August 21, 2026, by Jitka Plesnikova, with the release of perl-URI version 5.36-1. Users are advised to upgrade their systems using the 'dnf' update program to mitigate the risk. The flaw could allow for non-standard A-label emissions, which may impact interoperability with other clients. The updates are available for installation, and users should apply them promptly to ensure system security. 2 sources 31

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Fedora 43 Faces Significant Issue with IDNA Normalization in perl

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