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GHSA-677m-j7p3-52f9 socket.io-parser

Fix: socketio/socket.io@719f9eb

GHSA-677m-j7p3-52f9 is a Improper Input Validation vulnerability in socket.io-parser. A fix is available for socket.io-parser — see the affected versions and patch details below.

socket.io allows an unbounded number of binary attachments

Also known asCVE-2026-33151
Published
Mar 18, 2026
Updated
Sep 10, 2026
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Sep 18, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-677m-j7p3-52f9.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs43th percentile — riskier than 43% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

3 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

250other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
socket.io-parsernpm
24.2Mdownloads / week

Description

Impact

A specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory.

Patches

Version rangeUsed byFixed version
>=4.0.0 <4.2.6[email protected] and [email protected]4.2.6
>=3.4.0 <3.4.4[email protected]3.4.4
<3.3.5[email protected]3.3.5

Workarounds

There is no known workaround except upgrading to a safe version.

For more information

If you have any questions or comments about this advisory:

  • Open a discussion here

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
📦npmsocket.io-parserall versions3.3.5npm install socket.io-parser@3.3.5
📦npmsocket.io-parser3.4.0&&< 3.4.43.4.4npm install socket.io-parser@3.4.4
📦npmsocket.io-parser4.0.0&&< 4.2.64.2.6npm install socket.io-parser@4.2.6

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for socket.io-parser, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update socket.io-parser to 3.3.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-677m-j7p3-52f9 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-677m-j7p3-52f9 can be triaged on real exposure rather than presence alone.

Tailored to GHSA-677m-j7p3-52f9. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact A specially crafted Socket.IO packet can make the server wait for a large number of binary attachments and buffer them, which can be exploited to make the server run out of memory. ### Patches | Version range | Used by | Fixed version | |------------------|--------------------------------------------|---------------| | `>=4.0.0 <4.2.6` | `[email protected]` and `[email protected]` | `4.2.6` | | `>=3.4.0 <3.4.4` | `[email protected]` | `3.4.4` | | `<3.3.5` | `[email protected]` |
O3 Security · Impact-Aware SCA

Is GHSA-677m-j7p3-52f9 in your dependencies?

O3 Security finds GHSA-677m-j7p3-52f9 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-677m-j7p3-52f9: socket.io-parser | O3 Security