Jinja vulnerable to HTML attribute injection when passing user input as keys to xmlattr filter

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.4 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

EPSS

• CVE-2024-34064: 0.98% estimated exploitation activity in the next 30 days; percentile 62.23 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

The xmlattr filter in affected versions of Jinja accepts keys containing non-attribute characters. XML/HTML attributes cannot contain spaces, /, , or =, as each would then be interpreted as starting a separate attribute. If an application accepts keys (as opposed to only values) as user input, and renders these in pages that other users see as well, an attacker could use this to inject other attributes and perform XSS. The fix for the previous GHSA-h5c8-rqwp-cp95 CVE-2024-22195 only addressed spaces but not other characters. Accepting keys as user input is now explicitly considered an unintended use case of the xmlattr filter, and code that does so without otherwise validating the input should be flagged as insecure, regardless of Jinja version. Accepting values as user input continues to be safe.

Published by the source

6 May 2024, 14:20 UTC

Last modified by the source

10 Sep 2026, 03:50 UTC

Source last checked

26 Oct 2026, 13:35 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-h75v-3vvj-5mfj

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-h75v-3vvj-5mfj

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# Patch Next advisory brief: CVE-2024-34064

Advisory: Jinja vulnerable to HTML attribute injection when passing user input as keys to xmlattr filter
IDs: CVE-2024-34064, GHSA-h75v-3vvj-5mfj
Record: https://patchnext.com/advisories/cve-2024-34064 (revision 2, source checked 26 Oct 2026, 13:35 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: jinja2 3.1.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI jinja2: affected < 3.1.4; fixed in 3.1.4

## Suggested inspection (read-only)
- `python -m pip show jinja2`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on jinja2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-h75v-3vvj-5mfj (OSV record GHSA-h75v-3vvj-5mfj lists affected ranges: PyPI jinja2 >=0 <3.1.4 (fixed))
- Verified: https://github.com/advisories/GHSA-h75v-3vvj-5mfj (GitHub-reviewed advisory GHSA-h75v-3vvj-5mfj lists affected ranges: PyPI jinja2 >=0 <3.1.4)

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