CVE-2026-122299jelmer dulwich vulnerability
CVE-2026-122299 is a vulnerability in jelmer dulwich, rated high (8.6 on CVSS 4.0).
Why this priority: High severity, with no exploitation signal yet.
Published · Updated · NVD status: Deferred
What it is
The record does not classify the weakness yet; the description below says what the reporter found.
How it is reached
An attacker can exploit it over the network, without an account, but someone has to act first, such as opening a file or following a link.
What an attacker gains
A successful attack can read the data it protects, change data or behaviour and take it offline.
Is it being exploited?
There is no public report of exploitation yet. EPSS estimates a 0.33% chance of exploitation activity in the next 30 days, higher than 26% of scored CVEs.
What to do
- Upgrade jelmer dulwich to 1.2.20 or later.
- Until it is patched, keep it off the internet or behind a VPN, allowlist or authenticating proxy.
- Warn the people who use it, and filter files and links on the way in.
Description from NVD
Dulwich before 1.2.20 contains a commit object parsing vulnerability where the read path in _parse_commit resolves a duplicate tree header to the last occurrence instead of the first, diverging from core git's resolution behavior, while Poetry 2.5.1 ships this version and uses dulwich by default for git dependency installation. Attackers can craft a commit object with two tree headers so that reviewers and CI using git see a benign tree while Poetry's dulwich-based checkout resolves to a different attacker-controlled tree containing malicious build scripts such as setup.py, resulting in unreviewed code execution on the install or build host.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- jelmer dulwich. Start from where it runs and what it is connected to.
Trust boundaries in play
- Internet-facing entry points. No account is needed. Any instance reachable from outside your perimeter, through a load balancer, gateway, VPN or exposed admin port, is in scope.
- People who open files and links. Mail, chat and browsers are the delivery path.
Questions to answer about your own systems
- Where does jelmer dulwich run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.