CVE-2026-0708
Libucl: libucl: denial of service via embedded null byte in ucl input
- Published
- Updated
- Reserved
- Assigned by
- fedora
Description
A 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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| fedoraCNA (assigner) | 3.1 | High8.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:H |
| NVDNVD · Analyzed | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.40% · top 65% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: poc · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.3.
Weakness
Affected products
What to do
Workaround: 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.
References (3)
- https://access.redhat.com/security/cve/CVE-2026-0708 (opens in a new tab)vdb-entryx_refsource_REDHAT
- RHBZ#2427770 (opens in a new tab)issue-trackingx_refsource_REDHAT
- https://github.com/vstakhov/libucl/issues/323 (opens in a new tab)exploit
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-0708)Record last updated .