Description
The XListFonts function in X.org libX11 before 1.6.4 might allow remote X servers to gain privileges via vectors involving length fields, which trigger out-of-bounds write operations.
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 | libx11 | 2:1.6.4-1 | — |
| Debian 13 | libx11 | 2:1.6.4-1 | — |
| Debian 12 | libx11 | 2:1.6.4-1 | — |
| Debian 7 | libx11 | 2:1.5.0-1+deb7u3 | DLA-684-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libx11 | 2:1.6.4-3ubuntu0.1 | USN-3758-1 |
| Ubuntu 16.04 LTS | libx11 | 2:1.6.3-1ubuntu2.1 | USN-3758-1 |
| Ubuntu 14.04 LTS | libx11 | 2:1.6.2-1ubuntu2.1 | USN-3758-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.3 | libx11 | 1.6.3-r3 | — |
| Alpine v3.2 | libx11 | 1.6.3-r1 | — |
Advisories 2
- USN-3758-1 libx11 vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-684-1 libx11 - security update Debian Security (DSA / DLA) · Mar 9, 2026
References
- 1036945 vdb-entry
- USN-3758-2 vendor-advisory
- https://cgit.freedesktop.org/xorg/lib/libX11/commit/?id=8c29f1607a31dac0911e45a0dd3d74173822b3c9
- GLSA-201704-03 vendor-advisory
- [xorg-announce] 20161004 X.Org security advisory: Protocol handling issues in X Window System client libraries mailing-list
- [oss-security] 20161004 Re: X.Org security advisory: Protocol handling issues in X Window System client libraries mailing-list
- [oss-security] 20161004 X.Org security advisory: Protocol handling issues in X Window System client libraries mailing-list
- 93362 vdb-entry
- USN-3758-1 vendor-advisory
- FEDORA-2016-0df69ab477 vendor-advisory