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Fencer Intel
critical 9.9

CVE-2026-53942 json

Conda Organization Infrastructure: Pwn Request in update workflow allows PR-controlled template rendering with SYNC_TOKEN

published 4mo ago modified 19d ago also EUVD-2026-109068 , GHSA-pf87-fcg3-wjfh

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository conda/infrastructure. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
9.9
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits
0
none known

Summary

Conda Organization Infrastructure is a centralized location for infrastructure codes. Prior to commit 9c0f238, a GitHub Actions Pwn Request vulnerability appears to remain present in conda/conda. The affected workflow is .github/workflows/update.yml. It is triggered by issue_comment events containing @conda-bot render or @conda-bot recreate. For the render path, the workflow obtains the pull request head repository and branch from the PR API, checks out that PR-controlled repository/ref using secrets.SYNC_TOKEN, and then runs conda/actions/template-files@7f6830b1428a9bd47f0b068892c77eae95207037. The external template-files action reads its default configuration and templates from the checked-out working directory. In the confirmed finding, that action uses an unsandboxed Jinja2 environment to render attacker-controlled template content. This creates a Pwn Request chain in which an untrusted PR/comment path can reach template rendering in a privileged token context. This issue has been patched via commit 9c0f238.

Patch / fix

Is CVE-2026-53942 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
19d ago

Exploit prediction

0.33% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 9.9 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L

Affected products

  • conda infrastructure

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of conda/infrastructure published their own advisory on GitHub. Reviewed sources take precedence over it.