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Unratedamended

ReDoS via long UserAgent header in ua-parser

CVE-2017-16086GHSA-pmg9-p9r2-6q87

What to do

Vendor response not established. Follow the primary source's mitigation guidance and check back for a fix.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm ua-parser

    Affected
    <= 0.3.5
    Fixed in
    no fixed version recorded

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
  • CVE-2017-16086: 9.10% estimated exploitation activity in the next 30 days; percentile 95.31 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Affected versions of ua-parser are vulnerable to regular expression denial of service when given a specially crafted User-Agent header. Recommendation No patch is currently available for this vulnerability. The best mitigation is currently to avoid using this package, using a different, functionally equivalent package such as useragent.

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-pmg9-p9r2-6q87

  2. Revision 1 · created ·

    Published from osv record GHSA-pmg9-p9r2-6q87

Agent brief

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2017-16086

Advisory: ReDoS via long UserAgent header in ua-parser
IDs: CVE-2017-16086, GHSA-pmg9-p9r2-6q87
Record: https://patchnext.com/advisories/cve-2017-16086 (revision 2, source checked 26 Oct 2026, 12:08 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm ua-parser: affected <= 0.3.5

## Suggested inspection (read-only)
- `npm ls ua-parser --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on ua-parser.
- 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-pmg9-p9r2-6q87 (OSV record GHSA-pmg9-p9r2-6q87 lists affected ranges: npm ua-parser >=0 <=0.3.5)
- Verified: https://github.com/advisories/GHSA-pmg9-p9r2-6q87 (GitHub-reviewed advisory GHSA-pmg9-p9r2-6q87 lists affected ranges: npm ua-parser >=0 <=0.3.5)

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