The stringprep_utf8_nfkc_normalize function in lib/nfkc.c in libidn before 1.33 allows…
Priority LOW 39CWE-125Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- Will not fix Red Hat: no fix planned
Attack profile from CVSS 3.0 · NVD. Fix status from CNA and Red Hat. Impact type from CWE-125 and the CVSS impact.
Summary
The stringprep_utf8_nfkc_normalize function in lib/nfkc.c in libidn before 1.33 allows context-dependent attackers to cause a denial of service (out-of-bounds read and crash) via crafted UTF-8 data.
Why it matters now
EPSS 0.03878 90th percentileScored 2026-11-07
Fix Will not fix Red Hat: no fix planned
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 5 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Will not fix |
| Red Hat Enterprise Linux 7 | Affected | No fix planned: Will not fix |
Timeline
- 2026-10-02 Threatist record created from CVE-2016-6263
- 2026-10-03 Alias added: GHSA-4q6w-2734-9q8x
- 2026-10-14 EPSS moved to the 90th–95th percentile
References
Patch 1
Advisory 8
Other 2
- [bookkeeper-issues] 20210628 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8
- [bookkeeper-issues] 20210629 [GitHub] [bookkeeper] padma81 opened a new issue #2746: Security Vulnerabilities in CentOS 7 image, Upgrade image to CentOS 8
More GNU Libidn vulnerabilities
- TI-2016-05364 idn in libidn before 1.33 might allow remote attackers to obtain sensitive memory… CVSS 3.0HIGH 7.5
- TI-2015-07361 idn in GNU libidn before 1.33 might allow remote attackers to obtain sensitive memory… CVSS 3.0HIGH 7.5
- TI-2016-05363 The idna_to_ascii_4i function in lib/idna.c in libidn before 1.33 allows… CVSS 3.0HIGH 7.5
- TI-2015-01846 The stringprep_utf8_to_ucs4 function in libin before 1.31, as used in jabberd2, allows… CVSS 2.0HIGH 7.5
- TI-2026-41060 GNU libidn before 1.44 is prone to out-of-bounds reads of uninitialized memory in the… CVSS 3.1MEDIUM 4.0
Sources
- CVE-2016-6263 · CVE Program
- CVE-2016-6263 · NVD
- FIRST EPSS
- GHSA-4q6w-2734-9q8x · GitHub Advisory Database · CC BY 4.0
- CVE-2016-6263 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences