JWT leak via Open Redirect in Programmatic access

Exploitation

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

CVSS

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

EPSS

• CVE-2021-29651: 0.66% estimated exploitation activity in the next 30 days; percentile 51.54 (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.

Impact Using programmatic access on protected sites, one can get a signed login URL with pomeriumredirecturi set to an arbitrary URL. Then, if the user has already logged into Pomerium, they will be redirected to the specified pomeriumredirecturi with a JWT attached. This allows an outside attacker to get a signed login URL that, upon visiting it, will redirect a victim to the attacker’s site. This creates an issue of Open Redirect and, more seriously, JWT leakage. With a leaked JWT, the attacker will be able to unveil the victim’s identity (.e.g. email address) by supplying the JWT to the authenticate service or verify.pomerium.com. In addition, if an application integrating Pomerium only verifies the iss claim and others but not the aud claim, the attacker will be able to access it as the victim. Specific Go Packages Affected github.com/pomerium/pomerium/proxy Patches Patched in Pomerium v0.13.4 For more information If you have any questions or comments about this advisory Open an…

Published by the source

21 May 2021, 16:24 UTC

Last modified by the source

2 Oct 2023, 12:09 UTC

Source last checked

26 Oct 2026, 14:59 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-35vc-w93w-75c2

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# Patch Next advisory brief: CVE-2021-29651

Advisory: JWT leak via Open Redirect in Programmatic access
IDs: CVE-2021-29651, GHSA-35vc-w93w-75c2
Record: https://patchnext.com/advisories/cve-2021-29651 (revision 1, source checked 26 Oct 2026, 14:59 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/pomerium/pomerium 0.13.4. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/pomerium/pomerium: affected < 0.13.4; fixed in 0.13.4

## Suggested inspection (read-only)
- Go github.com/pomerium/pomerium: check the installed version with your package manager.

## 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 github.com/pomerium/pomerium.
- 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://github.com/advisories/GHSA-35vc-w93w-75c2 (GitHub-reviewed advisory GHSA-35vc-w93w-75c2 lists affected ranges: Go github.com/pomerium/pomerium >=0 <0.13.4)

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