probe-image-size: Quadratic-time Denial of Service in the SVG Parser

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-2026-104861: 0.43% estimated exploitation activity in the next 30 days; percentile 36.84 (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.

Overview probe-image-size scans the SVG header with a searching regular expression, /<[-.:a-zA-Z0-9][^]/. On input that contains many < characters but no , the engine restarts the [^] scan at every < position and runs to end of input each time, giving quadratic time complexity. Both the synchronous and the streaming parser are affected. Impact Every entry point that reaches the SVG parser is affected: probe.sync(), probe(stream) and probe(url). The URL form is the most exposed one — the input is fetched from a remote host, so an attacker only needs to supply a link. Processing a crafted buffer blocks the Node.js event loop at 100% CPU for the whole duration. In production environments such as upload validators, image proxies or link unfurl services, a small number of concurrent requests is enough to deny service. Root Cause Analysis Two independent problems. 1. Absence of input size cap in the sync path. lib/parsesync/svg.js copied the entire buffer into a string and matched against…

Published by the source

2 Oct 2026, 23:18 UTC

Last modified by the source

2 Oct 2026, 23:30 UTC

Source last checked

26 Oct 2026, 13:06 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-gjj5-9665-rwrc

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GHSA-gjj5-9665-rwrc

3. Revision 1 · created · 23 Oct 2026

   Published from ghsa record GHSA-gjj5-9665-rwrc

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# Patch Next advisory brief: CVE-2026-104861

Advisory: probe-image-size: Quadratic-time Denial of Service in the SVG Parser
IDs: CVE-2026-104861, GHSA-gjj5-9665-rwrc
Record: https://patchnext.com/advisories/cve-2026-104861 (revision 3, source checked 26 Oct 2026, 13:06 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: probe-image-size 7.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm probe-image-size: affected <= 7.3.0; fixed in 7.4.0

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

## 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 probe-image-size.
- 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-gjj5-9665-rwrc (GitHub-reviewed advisory GHSA-gjj5-9665-rwrc lists affected ranges: npm probe-image-size >=0 <=7.3.0)
- Verified: https://osv.dev/vulnerability/GHSA-gjj5-9665-rwrc (OSV record GHSA-gjj5-9665-rwrc lists affected ranges: npm probe-image-size >=0 <7.4.0 (fixed))

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