Description
GNU libidn before 1.44 is prone to out-of-bounds reads of uninitialized memory in the ToUnicode APIs because of mishandling in idna_to_unicode_internal. The affected code is not present in libidn2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| GNU | libidn | < 1.44 | 1.44 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | libidn | 1.44-1 | — |
| Debian 13 | libidn | No fix yet | — |
| Debian 12 | libidn | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | libidn | 1.43-2ubuntu0.26.04.1 | USN-8521-1 |
| Ubuntu 25.10 | libidn | No fix yet | — |
| Ubuntu 24.04 LTS | libidn | 1.42-1ubuntu0.1 | USN-8521-1 |
| Ubuntu 22.04 LTS | libidn | 1.38-4ubuntu1.1 | USN-8521-1 |
| Ubuntu 20.04 LTS | libidn | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libidn | No fix yet | — |
| Ubuntu 16.04 LTS | libidn | No fix yet | — |
| Ubuntu 14.04 LTS | libidn | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Hardened Images 1 | idn2 +2 | 2.3.8-4.hum1 | RHSA-2026:42125 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | libidn | 1.34-150000.3.5.1 | SUSE-SU-2026:4000-1 |
| SLES 12 SP5 | libidn | 1.28-5.9.1 | SUSE-SU-2026:4081-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | libidn | 1.43-160000.3.1 | SUSE-SU-2026:23621-1 |
| SLES 16.0 | libidn | 1.43-160000.3.1 | SUSE-SU-2026:23621-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | libidn | 1.43-160000.3.1 | openSUSE-SU-2026:21758-1 |
Advisories 6
- RHSA-2026:42125 Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update Red Hat Security Advisories (RHSA) · Oct 6, 2026
- SUSE-SU-2026:23621-1 Security update for libidn SUSE / openSUSE Security Updates · Sep 29, 2026
- SUSE-SU-2026:4081-1 Security update for libidn SUSE / openSUSE Security Updates · Sep 13, 2026
- SUSE-SU-2026:4000-1 Security update for libidn SUSE / openSUSE Security Updates · Sep 13, 2026
- openSUSE-SU-2026:21758-1 Security update for libidn SUSE / openSUSE Security Updates · Sep 9, 2026
- USN-8521-1 libidn vulnerability Ubuntu Security Notices (USN) · Jul 9, 2026