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

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

probe-image-size gets image dimensions without downloading the entire file. Prior to 7.4.0, lib/parse_sync/svg.js and lib/parse_stream/svg.js use the searching regular expression /<[-_.:a-zA-Z0-9][^>]*>/, which repeatedly scans to the end of input when attacker-controlled data contains many less-than characters without a closing greater-than character. The synchronous parser converts and scans the full supplied buffer without an input cap, while the streaming parser reparses the complete accumulated SVG prefix for every received chunk. The probe.sync(), probe(stream), and probe(url) entry points can therefore block the Node.js event loop at full CPU, and attacker-controlled chunking can amplify the streaming cost. This issue is fixed in version 7.4.0.

Source published

2 Oct 2026 17:56:15 UTC

Source modified

2 Oct 2026 18:20:12 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

probe-image-size gets image dimensions without downloading the entire file. Prior to 7.4.0, lib/parse_sync/svg.js and lib/parse_stream/svg.js use the searching regular expression /<[-_.:a-zA-Z0-9][^>]*>/, which repeatedly scans to the end of input when attacker-controlled data contains many less-than characters without a closing greater-than character. The synchronous parser converts and scans the full supplied buffer without an input cap, while the streaming parser reparses the complete accumulated SVG prefix for every received chunk. The probe.sync(), probe(stream), and probe(url) entry points can therefore block the Node.js event loop at full CPU, and attacker-controlled chunking can amplify the streaming cost. This issue is fixed in version 7.4.0.

Source published

Oct 2, 2026, 5:56:15 PM (timezone not stated)

Source modified

Oct 2, 2026, 6:20:12 PM (timezone not stated)

Observed here

11 Nov 2026 05:30:36 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

probe-image-size gets image dimensions without downloading the entire file. Prior to 7.4.0, lib/parse_sync/svg.js and lib/parse_stream/svg.js use the searching regular expression /<[-_.:a-zA-Z0-9][^>]*>/, which repeatedly scans to the end of input when attacker-controlled data contains many less-than characters without a closing greater-than character. The synchronous parser converts and scans the full supplied buffer without an input cap, while the streaming parser reparses the complete accumulated SVG prefix for every received chunk. The probe.sync(), probe(stream), and probe(url) entry points can therefore block the Node.js event loop at full CPU, and attacker-controlled chunking can amplify the streaming cost. This issue is fixed in version 7.4.0.

Source published

2 Oct 2026 18:17:02 UTC

Source modified

2 Oct 2026 19:16:41 UTC

Observed here

25 Oct 2026 04:17:29 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

## 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/parse_sync/svg.js` copied the entire buffer into a string and matched against it. There was no size limit at all, so cost scaled with the size of the attacker-supplied buffer. 2. **Repeated rescanning in the stream path.** `lib/parse_stream/svg.js` did cap accumulated data at 64 KB, but called `parseSvg(str)` on the whole accumulated string on *every* chunk, giving `O(chunks × N²)`. The cap does not help here: the more chunks the input is split into, the more times the quadratic scan is repeated. Chunk size is influenced by the sender. `highWaterMark` (16 KB) is a buffering threshold, not a lower bound — a socket read returns whatever has arrived. A server that writes one byte at a time produces one-byte chunks; this was confirmed against the real `needle` pipeline with default options. The original report identified (1) only, and stated that the 64 KB cap mitigates the streaming path. It does not. ## Proof of Concept (PoC) Synchronous: ```js const probe = require('probe-image-size') // ~200 KB of '<a' — contains '<' but never '>' probe.sync(Buffer.from('<a'.repeat(100000), 'latin1')) ``` Streaming — the same payload split into chunks, slower per byte than the synchronous form: ```js const { Readable } = require('stream') const probe = require('probe-image-size') const payload = Buffer.from('<a'.repeat(32768), 'latin1') const chunks = [] for (let i = 0; i < payload.length; i += 4096) chunks.push(payload.subarray(i, i + 4096)) await probe(Readable.from(chunks)) ``` Measurements on the maintainer's machine: | path | input | time | | --- | --- | --- | | `probe.sync()` | 25 KB | 0.9 s | | `probe.sync()` | 50 KB | 5.5 s | | `probe.sync()` | 100 KB | 18 s | | `probe.sync()` | 200 KB | 54 s | | `probe(stream)` | 64 KB, 1 chunk | 1.6 s | | `probe(stream)` | 64 KB, 4 chunks | 2.9 s | | `probe(stream)` | 64 KB, 16 chunks | 9.6 s |

Source published

2 Oct 2026 23:18:02 UTC

Source modified

2 Oct 2026 23:30:06 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH