Description
Heap-based buffer overflow in ultra.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeds what is specified by the tile dimensions.
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 | libvncserver | 0.9.11+dfsg-1 | — |
| Debian 13 | libvncserver | 0.9.11+dfsg-1 | — |
| Debian 13 | veyon | 4.1.4+repack1-1 | — |
| Debian 12 | libvncserver | 0.9.11+dfsg-1 | — |
| Debian 12 | veyon | 4.1.4+repack1-1 | — |
| Debian 8 | italc | 1:2.0.2+dfsg1-2+deb8u1 | DLA-1979-1 |
| Debian 8 | libvncserver | 0.9.9+dfsg2-6.1+deb8u2 | DSA-3753-1 |
| Debian 7 | libvncserver | 0.9.9+dfsg-1+deb7u2 | DLA-777-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | italc | 1:2.0.2+dfsg1-4ubuntu0.1 | USN-4587-1 |
| Ubuntu 16.04 LTS | libvncserver | 0.9.10+dfsg-3ubuntu0.16.04.1 | USN-3171-1 |
| Ubuntu 14.04 LTS | libvncserver | 0.9.9+dfsg-1ubuntu1.2 | USN-3171-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP3 | LibVNCServer | 0.9.9-17.5.1 | SUSE-SU-2018:0830-1 |
| SLES 12 SP2 | LibVNCServer | 0.9.9-17.5.1 | SUSE-SU-2018:0830-1 |
| SLES 12 SP2 | tigervnc | 1.6.0-16.4 | SUSE-SU-2017:0622-1 |
| SLES 12 SP1 | tigervnc | 1.4.3-19.1 | SUSE-SU-2017:0519-1 |
| SLES 11 SP4 | LibVNCServer | 0.9.1-159.1 | SUSE-SU-2017:0104-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP3 | LibVNCServer | 0.9.9-17.5.1 | SUSE-SU-2018:0830-1 |
| SLES for SAP 12 SP2 | LibVNCServer | 0.9.9-17.5.1 | SUSE-SU-2018:0830-1 |
| SLES for SAP 12 SP2 | tigervnc | 1.6.0-16.4 | SUSE-SU-2017:0622-1 |
| SLES for SAP 12 SP1 | tigervnc | 1.4.3-19.1 | SUSE-SU-2017:0519-1 |
| SLES for SAP 11 SP4 | LibVNCServer | 0.9.1-159.1 | SUSE-SU-2017:0104-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.23 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.22 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.21 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.20 | libvncserver | 0.9.11-r0 | — |
Show 18 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.18 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.17 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.16 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.15 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.14 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.13 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.12 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.11 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.10 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.9 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.8 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.7 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.6 | libvncserver | 0.9.11-r0 | — |
| Alpine v3.5 | libvncserver | 0.9.10-r2 | — |
| Alpine v3.4 | libvncserver | 0.9.10-r2 | — |
| Alpine v3.3 | libvncserver | 0.9.10-r2 | — |
| Alpine v3.2 | libvncserver | 0.9.10-r2 | — |
Advisories 9
- USN-4587-1 italc vulnerabilities Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-3171-1 libvncserver vulnerabilities Ubuntu Security Notices (USN) · Apr 22, 2026
- DLA-777-1 libvncserver - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3753-1 libvncserver - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-1979-1 italc - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2018:0830-1 Security update for LibVNCServer SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0622-1 Security update for tigervnc SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0104-1 Security update for LibVNCServer SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2017:0519-1 Security update for tigervnc SUSE / openSUSE Security Updates · Feb 4, 2026
References
- 95170 vdb-entry
- https://github.com/LibVNC/libvncserver/pull/137
- DSA-3753 vendor-advisory
- GLSA-201702-24 vendor-advisory
- https://github.com/LibVNC/libvncserver/releases/tag/LibVNCServer-0.9.11
- [debian-lts-announce] 20191030 [SECURITY] [DLA 1979-1] italc security update mailing-list
- USN-4587-1 vendor-advisory