Libucl: libucl: denial of service via embedded null byte in ucl input

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-0708
StatePUBLISHED
Assignerfedora
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-17 04:16:07 UTC
Updated2026-05-11 17:14:50 UTC
DescriptionA flaw was found in libucl. A remote attacker could exploit this by providing a specially crafted Universal Configuration Language (UCL) input that contains a key with an embedded null byte. This can cause a segmentation fault (SEGV fault) in the `ucl_object_emit` function when parsing and emitting the object, leading to a Denial of Service (DoS) for the affected system.

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

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

EPSS: 0.001410000 probability, percentile 0.337830000 (date 2026-05-12)

Problem Types: CWE-125 | CWE-125 Out-of-bounds Read

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
3.1[email protected]Secondary8.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:H
3.1CNACVSS8.3HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Vstakhov Libucl All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Libucl Libucl affected 3e7f023e184e06f30fb5792dacd9dd0f8b692f1b git Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com Third Party Advisory, Issue Tracking
access.redhat.com/security/cve/CVE-2026-0708 [email protected] access.redhat.com Third Party Advisory
github.com/vstakhov/libucl/issues/323 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com Issue Tracking, Vendor Advisory, Exploit
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2026-01-08T03:30:46.275ZReported to Red Hat.
CNA2025-05-15T00:00:00.000ZMade public.

Workarounds

CNA: To mitigate this issue, applications utilizing `libucl` should avoid processing untrusted input that contains keys with embedded null bytes, especially when operating in `UCL_PARSER_ZEROCOPY` mode. Restricting input to trusted sources can reduce exposure.

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