The idna_to_ascii_4i function in lib/idna.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 idna_to_ascii_4i function in lib/idna.c in libidn before 1.33 allows context-dependent attackers to cause a denial of service (out-of-bounds read and crash) via 64 bytes of input.
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
CPE configurations NVD · 5
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:* | 42.1 | Vulnerable | openSUSE |
| cpe:2.3:a:gnu:libidn:*:*:*:*:*:*:*:* | up to 1.32 | Vulnerable | GNU |
| cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:* | 12.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:* | 14.04 | Vulnerable | Canonical |
| cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:* | 16.04 | Vulnerable | Canonical |
- cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:* Versions 42.1 Vulnerable ·openSUSE
- cpe:2.3:a:gnu:libidn:*:*:*:*:*:*:*:* Versions up to 1.32 Vulnerable ·GNU
- cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:* Versions 12.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:* Versions 14.04 Vulnerable ·Canonical
- cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:* Versions 16.04 Vulnerable ·Canonical
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-2016-6261
- 2026-10-03 Alias added: GHSA-hr7q-x7xm-q959
- 2026-10-14 EPSS moved to the 90th–95th percentile
References
Patch 1
Advisory 7
- [oss-security] 20160721 Re: CVE request: multiple issues fixed in GNU libidn 1.33
- openSUSE-SU-2016:2135
- [oss-security] 20160720 CVE request: multiple issues fixed in GNU libidn 1.33
- DSA-3658
- [help-libidn] 20160720 Libidn 1.33 released
- USN-3068-1
- [help-libidn] 20150709 out of bounds stack read in function idna_to_ascii_4i
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
Sources
- CVE-2016-6261 · CVE Program
- CVE-2016-6261 · NVD
- FIRST EPSS
- GHSA-hr7q-x7xm-q959 · GitHub Advisory Database · CC BY 4.0
- CVE-2016-6261 · Red Hat security data · CC BY 4.0
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