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Fencer Vulns
medium 4.0

CVE-2026-57053 json

GNU libidn before 1.44 is prone to out-of-bounds reads of uninitialized memory in the ToUnicode APIs...

published 2026-06-23 4 mo ago modified 2026-10-25 14 d ago also EUVD-2026-38523 , GHSA-xpv7-vm32-p7wv , JLSEC-2026-667

cvss
4.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

GNU libidn before 1.44 is prone to out-of-bounds reads of uninitialized memory in the ToUnicode APIs because of mishandling in idna_to_unicode_internal. The affected code is not present in libidn2.

Patch / fix

  • julia libidn_jll 1.44.0+0
  • GNU libidn 1.44
  • libidn Debian 14 1.44-1

debian advisories DEBIAN-CVE-2026-57053

  • libidn Ubuntu 22.04 LTS 1.38-4ubuntu1.1
  • libidn Ubuntu 24.04 LTS 1.42-1ubuntu0.1
  • libidn Ubuntu 26.04 LTS 1.43-2ubuntu0.26.04.1

ubuntu advisories UBUNTU-CVE-2026-57053

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • idn2 hummingbird 1 2.3.8-4.hum1
  • libidn2 hummingbird 1 2.3.8-4.hum1

red hat advisories RHSA-2026:42125

  • libidn SLE Module for Basesystem 15 SP7 1.34-150000.3.5.1
  • libidn SLES for SAP applications 16.0, SLES 16.0 1.43-160000.3.1
  • libidn SLES LTSS Extended Security 12 SP5 1.28-5.9.1

suse advisories SUSE-SU-2026:4081-1SUSE-SU-2026:4000-1SUSE-SU-2026:23621-1

  • libidn openSUSE Leap 16.0 1.43-160000.3.1

opensuse advisories openSUSE-SU-2026:21758-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-57053 updated cvss 2.9

libidn: GNU libidn: Out-of-bounds read in ToUnicode APIs

  • Red Hat Migration Toolkit for Containers libidn 1.34-5.el8
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux 6 libidn 1.34-5.el8
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 7 emacs-libidn, libidn 1.34-5.el8 Red Hat Enterprise Linux 8 libidn 1.34-5.el8
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Hardened Images idn2 2.3.8-4.hum1, libidn2 2.3.8-4.hum1
    fixed: vendor fix RHSA-2026:42125
  • Red Hat Enterprise Linux 8 idn2, libidn2, libidn2 2.3.7-3.el10 Red Hat Enterprise Linux 9 idn2, libidn2 2.3.7-3.el10 Red Hat Enterprise Linux 10 libidn2 2.3.7-3.el10
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
4 mo ago

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • lists.gnu.org https://lists.gnu.org/archive/html/help-libidn/2026-05/msg00000.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 4.0 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
NVD 3.1 2.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
OSV 3.1 2.5 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
julia libidn_jll
<1.44.0+0
1.44.0+0

Affected products

  • GNU libidn

Classification

Weakness
  • CWE-1284 Improper Validation of Specified Quantity in Input

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.