How severe is CVE-2016-6261?

CVE-2016-6261 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2016-6261 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-6261?

CVE-2016-6261 primarily affects Gnu Libidn. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2016-6261?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2016-6261 published?

CVE-2016-6261 was published on 2016-09-07 and last updated on 2026-06-17.

CVE-2016-6261

CVE-2016-6261 is a high-severity vulnerability in Gnu Libidn with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-125
Affected product: Gnu Libidn
Published: 2016-09-07
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2016-6261?: 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.
How severe is CVE-2016-6261?: CVE-2016-6261 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2016-6261 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-6261?: CVE-2016-6261 primarily affects Gnu Libidn. In total, 5 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-6261?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2016-6261 published?: CVE-2016-6261 was published on 2016-09-07 and last updated on 2026-06-17.

References

Affected products (5)

cpe:2.3:o:opensuse:leap:42.1:*:*:*:*:*:*:*
cpe:2.3:a:gnu:libidn:*:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:12.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*

More vulnerabilities in Gnu Libidn

CVE-2016-6263 — High (CVSS 7.5): The stringprep_utf8_nfkc_normalize function in lib/nfkc.c in libidn before 1.33 allows context-dependent attackers to…
CVE-2016-6262 — High (CVSS 7.5): idn in libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero byte as…
CVE-2015-8948 — High (CVSS 7.5): idn in GNU libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero…
CVE-2015-2059 — High (CVSS 7.5): The stringprep_utf8_to_ucs4 function in libin before 1.31, as used in jabberd2, allows context-dependent attackers to…
CVE-2026-57053 — Medium (CVSS 4.0): GNU libidn before 1.44 is prone to out-of-bounds reads of uninitialized memory in the ToUnicode APIs because of…

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CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
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