Skip to main content
Public proof of conceptFix available

CVE-2023-26103

A public proof of concept exists; no exploitation attested.

  • Published2023-02-25
  • Fixed in1.31.0
  • WeaknessCWE-1333

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.

Timeline

dates in UTC
  1. 2023-02-2505:15CVE publishedNVD

Versions per branch

NVD · OSV
Deno
BranchAffectedFixed in
1.31< 1.31.01.31.0
1.x≥ 1.12.0, < 1.31.01.31.0

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As snyk, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • deno
    Affected
    • < 1.31.0fixed in 1.31.0semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2023-02-25

Fix

  1. Update Deno to 1.31.0

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionpoc2025-03-11
  • CNACVSS 3.15.3known since 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • CISA-ADPweakness (CWE)CWE-13332025-03-11
  • CNAweakness (CWE)CWE-1333known since 2026-10-23
  • NVDweakness (CWE)CWE-1333read 2026-10-23
  • FIRST EPSSEPSS score1.2 %2026-11-08
  • OSVaffected packages—
  • GitHub AdvisoriesadvisoryMODERATE2023-04-03

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
2023-02-25
Last Modified
2026-06-17
NVD status
Modified
GitHub Advisory
GHSA-jc97-h3h9-7xh6

Frequently asked questions

What is CVE-2023-26103?

Versions of the package deno before 1.31.0 are vulnerable to Regular Expression Denial of Service (ReDoS) due to the upgradeWebSocket function, which contains regexes in the form of /s*,s*/, used for splitting the Connection/Upgrade header. A specially crafted Connection/Upgrade header can be used to significantly slow down a web socket server.

Is CVE-2023-26103 actively exploited?

A proof-of-concept exploit exists for CVE-2023-26103, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2023-26103?

CVE-2023-26103 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Running deno? Hear about its next vulnerability

Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».

Get alerts for this productCISA KEV additions, November 2026Search CVEs

No credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database

Sources for this record