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NVD / CVE Program· CNA mitre

CVE-2026-57053: 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_unico

Noroxi assessment

Priority: Monitor (action score 10/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.13% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: libidn (Debian:14) 1.44-1; libidn (openSUSE:Leap 16.0) 1.43-160000.3.1; idn2 (Red Hat:hummingbird:1) 0:2.3.8-4.hum1.

Low priority for now. Upgrade to libidn (Debian:14) 1.44-1; libidn (openSUSE:Leap 16.0) 1.43-160000.3.1; idn2 (Red Hat:hummingbird:1) 0:2.3.8-4.hum1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

LowCVSS 2.5 · v3.1—No exploit Fix available
Published
Jun 23, 2026
Updated
Oct 25, 2026
EPSS
0.1% · 3th percentile

Report tools

JSON

Action score

10

Monitor

Low priority for now.

CVSS
10 / 40 · 2.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
2.5
CNA · mitre
4.0
1.5 point gap

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

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
gnulibidn

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • gnu libidn0.1.15 and later · before 1.44

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mitre). Independent of NVD's CPE analysis and usually ahead of it.

  • GNU libidn

    • before 1.44affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12libidnfrom 0—
Debian:14libidnbefore 1.44-11.44-1
openSUSE:Leap 16.0libidnbefore 1.43-160000.3.11.43-160000.3.1
Red Hat:hummingbird:1idn2before 0:2.3.8-4.hum10:2.3.8-4.hum1
Red Hat:hummingbird:1libidn2before 0:2.3.8-4.hum10:2.3.8-4.hum1
Red Hat:hummingbird:1libidn2-develbefore 0:2.3.8-4.hum10:2.3.8-4.hum1
SUSE:Linux Enterprise Module for Basesystem 15 SP7libidnbefore 1.34-150000.3.5.11.34-150000.3.5.1
SUSE:Linux Enterprise Server 16.0libidnbefore 1.43-160000.3.11.43-160000.3.1
SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5libidnbefore 1.28-5.9.11.28-5.9.1

Same product

gnu: all records

Other highest-scoring records for the same primary product.

  • CVE-2016-6262idn in libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero byte as input, which trigger
    32Monitor
  • CVE-2015-8948idn in GNU libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero byte as input, which tri
    32Monitor
  • CVE-2016-6263The stringprep_utf8_nfkc_normalize function in lib/nfkc.c in libidn before 1.33 allows context-dependent attackers to cause a denial of serv
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2015-2059Aug 12, 2015 · The stringprep_utf8_to_ucs4 function in libin before 1.31, as used in jabberd2, allows context-dependent attackers to read system memory and
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:libidn1.44-1 · Debian:14Package registry (OSV)
opensuse:libidn1.43-160000.3.1 · openSUSE:Leap 16.0Package registry (OSV)
red hat:idn20:2.3.8-4.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:libidn20:2.3.8-4.hum1 · Red Hat:hummingbird:1Package registry (OSV)
red hat:libidn2-devel0:2.3.8-4.hum1 · Red Hat:hummingbird:1Package registry (OSV)
suse:libidn1.43-160000.3.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
none
Integrity
low · data or configuration can be modified
Availability
none
Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
Low
Availability impact
None

Weakness class (CWE)

CWE-1284 · Improper Validation of Specified Quantity in Input

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records