Emmett-Core: Unhandled CookieError Exception Causing Denial of Service

Exploitation

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

CVSS

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

EPSS

• CVE-2026-25577: 0.31% estimated exploitation activity in the next 30 days; percentile 24.09 (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.

Summary The cookies property in emmettcore.http.wrappers.Request does not handle CookieError exceptions when parsing malformed Cookie headers. This allows unauthenticated attackers to trigger HTTP 500 errors and cause denial of service. Details Location: emmettcore/http/wrappers/init.py (line 64) Vulnerable Code: PoC Sending cookies containing special characters such as /(){} will result in insufficient error handling and a server error. After the same error occurs several times, the server cannot process it normally. This is server log. Impact This vulnerability allows unauthenticated attackers to cause denial of service and performance degradation by sending malformed Cookie headers. After this vulnerability occurs, we expect it to be difficult to use the normal service. patch /emmettcore/http/wrappers/init.py

Published by the source

10 Feb 2026, 14:33 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:36 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-x6cr-mq53-cc76

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-x6cr-mq53-cc76

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# Patch Next advisory brief: CVE-2026-25577

Advisory: Emmett-Core: Unhandled CookieError Exception Causing Denial of Service
IDs: CVE-2026-25577, GHSA-x6cr-mq53-cc76
Record: https://patchnext.com/advisories/cve-2026-25577 (revision 2, source checked 26 Oct 2026, 13:36 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: emmett-core 1.3.11. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI emmett-core: affected <= 1.3.10; fixed in 1.3.11

## Suggested inspection (read-only)
- `python -m pip show emmett-core`: 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 emmett-core.
- 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-x6cr-mq53-cc76 (OSV record GHSA-x6cr-mq53-cc76 lists affected ranges: PyPI emmett-core >=0 <1.3.11 (fixed))
- Verified: https://github.com/advisories/GHSA-x6cr-mq53-cc76 (GitHub-reviewed advisory GHSA-x6cr-mq53-cc76 lists affected ranges: PyPI emmett-core >=0 <=1.3.10)

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