CVE-2023-35989 is a high severity (7.8) integer overflow in GTKWave 3.3.115, in the LXT2 zlib block allocation, triggered by opening a crafted .lxt2 file. The record says it can lead to code execution. Debian's fixed packages are built from upstream 3.3.118, so update to that.
What's affected
The record lists GTKWave 3.3.115, from Tony Bybell, as the affected version. It names no other release and gives no fixed version.
The Debian security tracker fills in the fix side. Its fixed packages are built from upstream 3.3.118:
- Debian 10 (buster): 3.3.98+really3.3.118-0+deb10u1, in advisory DLA-3785-1.
- Debian 11 (bullseye): 3.3.104+really3.3.118-0+deb11u1, in advisory DSA-5653-1.
- Debian 12 (bookworm): 3.3.118-0.1~deb12u1, in advisory DSA-5653-1.
- Debian testing and unstable carry 3.3.121 and 3.3.127.
So the record and the distribution disagree in how they describe the range. The record says 3.3.115. The fixed builds are 3.3.118. Releases between the two are not covered by either source. Treat 3.3.118 as the version to reach, and confirm against the Talos report, which I could not open because it blocked my request. Other distributions may use their own version strings, so read your vendor's advisory.
Talos reported this one on its own, as TALOS-2023-1822. It concerns the way the LXT2 reader works out how much memory to allocate for zlib compressed blocks.
How to check if you're exposed
GTKWave is a desktop waveform viewer, so it usually sits on engineering workstations, lab machines and verification servers rather than production hosts. It also gets pulled into container images and build environments.
gtkwave --version
dpkg -s gtkwave | grep Version
brew list --versions gtkwave
Use the line that matches your system. On Debian or Ubuntu, compare the package version with the fixed builds listed above, and remember that distributions can backport fixes under older numbers, so read the package changelog for the CVE id if the number looks low.
Also look for shared directories where waveform files arrive, such as simulation output folders and vendor drops. The risk comes from opening a file, so knowing where untrusted files come from matters as much as the version number.
What to do now
- Find every machine, image and shared tool that has GTKWave installed, and record the version.
- Update to upstream 3.3.118 or later, or to your distribution's fixed package. On Debian, that means the update from DLA-3785-1 or DSA-5653-1.
- Until updated, do not open .lxt2 files from sources you do not trust, and do not open them on a machine that holds credentials or source code.
- Treat waveform files that arrive from vendors, contractors or the internet as untrusted input, and open them on a disposable machine where you can.
- Re-check the version after the update, including inside container images that were built earlier.
Why it matters
The weakness is CWE-190, integer overflow or wraparound. A size calculation produces a number that does not fit in the variable, so it wraps around to a small value. The program then allocates less memory than it needs and later writes more data than fits. The record says this lets a specially crafted .lxt2 file lead to arbitrary code execution when a victim opens it.
The score is 7.8 with a local vector and one required user action. It is not on CISA's Known Exploited Vulnerabilities list, and I found no claim of exploitation.
Integer overflows are a quiet cause of many memory bugs. The arithmetic looks harmless, and the damage shows up later in a different function. Fuzzing file parsers, and using checked arithmetic when sizes come from outside data, are the standard defences.
Try it yourself
GTKWave often rides along in lab and build images. This demo shows how a container image scan lists what is inside an image and what is vulnerable.
Click through it at your own pace, or open it full screen.
Quick check
What is an LXT2 file?
It is one of the waveform file formats GTKWave reads. The record says a crafted .lxt2 file can trigger the flaw.
Why does a size calculation lead to code execution?
If the size wraps to a small number, memory is under allocated and later writes go past the end. That is a description of the class, not of exploit steps.
Sources
- Debian Security Tracker entry for CVE-2023-35989
- Talos report TALOS-2023-1822 (cited by the record; blocked to automated fetch)
- Debian LTS announcement cited by the record (needs JavaScript; not read)
- Safeguard Gold entry for CVE-2023-35989
Last reviewed: 19 October 2026.
