Joi 17.13.6 before 17.13.9 and 18.2.5 before 18.3.1 Prototype Replacement via proto Language Key
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 17.13.9, 18.3.1
- Who is exposed
- Not reported
Do first: Upgrade to a fixed version: 17.13.9, 18.3.1.
- Exploitation?/40Exploitation: unknown (data gap). No CISA SSVC exploitation rating yet
- Exposure17/25No login or user action needed per the CVSS vector, reachable over the network without a login · Data gap: No advisory context yet
- Reach?/20Reach: unknown (data gap). No tracked technology or package matched
- Severity6.3/10CVSS 6.3
- No patch0/5No signal
What would change the score
- Would score about 68 if added to CISA KEV
- Would score about 63 if CISA's SSVC rates exploitation active
- Would score about 28 if advisories confirm default setups are exposed
CVE-2026-122131 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.3 (medium) and affects joi; fixed in 17.13.9 and 18.3.1.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 23/100 · provisional
- Fix
- Fixed in 17.13.9, 18.3.1
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Joi, a JavaScript data validation library, is affected by a prototype pollution flaw in its message compilation and merging code. A remote attacker who can supply untrusted message configuration, such as custom messages or validation options, without logging in can replace the messages prototype and alter or break validation error output and dependent logic.
Read the original description
Joi 17.13.6 before 17.13.9 and 18.2.5 before 18.3.1 contains a prototype pollution vulnerability in lib/messages.js compile() and merge() that fails to reject a proto language key. Attackers supplying untrusted message configuration via any().messages(), prefs, validate options or Joi.extend can replace the compiled messages prototype, altering or breaking validation error rendering and dependent logic.
What to do
Upgrade to a fixed version: 17.13.9, 18.3.1.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- hapijs joi
From 17.13.6 · fixed in 17.13.9; From 18.2.5 · fixed in 18.3.1
Evidence 7
- Advisory
- Patch
- Patch
- Patch
- Repository
Show all 7 sourcesShow fewer sources
- Repository
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-122131
Is CVE-2026-122131 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
Which versions are affected by CVE-2026-122131?
joi: from 17.13.6 before 17.13.9; from 18.2.5 before 18.3.1.Source: cve.now feed data
How do I fix CVE-2026-122131?
Upgrade to a fixed version: 17.13.9, 18.3.1.Source: cve.now feed data