CVE-2023-46233: crypto-js PBKDF2 1,000 times weaker than specified in 1993 and 1.3M times weaker than current standard

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.6%, percentile 50: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 50% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes crypto-js (npm) < 4.2.0, fixed in 4.2.0. Check your lockfile, including transitive dependencies.

What it is

crypto-js is a JavaScript library of crypto standards. Prior to version 4.2.0, crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and at least 1,300,000 times weaker than current industry standard. This is because it both defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005, and defaults to one single iteration, a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to preimage and collision attacks. If used to protect passwords, the impact is high. If used to generate signatures, the impact is high. Version 4.2.0 contains a patch for this issue. As a workaround, configure crypto-js to use SHA256 with at least 250,000 iterations.

From the GitHub advisory

Impact Summary Crypto-js PBKDF2 is 1,000 times weaker than originally specified in 1993, and [at least 1,300,000 times weaker than current industry standard][OWASP PBKDF2 Cheatsheet]. This is because it both (1) defaults to [SHA1][SHA1 wiki], a cryptographic hash algorithm considered insecure [since at least 2005][Cryptanalysis of SHA-1] and (2) defaults to [one single iteration][one iteration src], a 'strength' or 'difficulty' value specified at 1,000 when specified in 1993. PBKDF2 relies on iteration count as a countermeasure to [preimage][preimage attack] and [collision][collision attack] attacks.

Potential Impact:

1. If used to protect passwords, the impact is high. 2. If used to generate signatures, the impact is high.

Probability / risk analysis / attack enumeration:

1. [For at most $45,000][SHA1 is a Shambles], an attacker, given control of only the beginning of a crypto-js PBKDF2 input, can create a value which has identical cryptographic signature to any chosen known value. 4. Due to the [length extension attack] on SHA1, we can create a value that has identical signature to any unknown value, provided it is prefixed by a known value. It does not matter if PBKDF2 applies '[salt][cryptographic salt]' or '[pepper][cryptographic pepper]' or any other secret unknown to the attacker. It will still create an identical signature.

Weakness type: CWE-328, CWE-916, CWE-327.

Product: crypto-js (npm) · Assigned by: GitHub_M · Published: 2023-10-25

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: none (no login)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.64% probability of exploitation activity in the next 30 days; percentile 50.

Timeline

• 2023-10-25 — CVE record published by GitHub_M
• 2023-10-25 — GitHub-reviewed advisory GHSA-xwcq-pm8m-c4vf published (critical)
• 2026-06-23 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-xwcq-pm8m-c4vf github.com
2. CVE.org record CVE-2023-46233 cve.org
3. NVD entry CVE-2023-46233 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. lists.debian.org lists.debian.org

Critical npm advisories · Today’s Security Digest