CVE-2023-46133 is a critical-severity (CVSS 9.1) CWE-328 vulnerability in crypto-es. 1 public exploit reference exists, so weaponization risk is real. A fix is available for crypto-es — see the affected versions and patch details below.
crypto-es PBKDF2 1,000 times weaker than specified in 1993 and 1.3M times weaker than current standard
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.
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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 CVE-2023-46133.
EPSS Exploitation Probability
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.
How urgent is this, really
CVE-2023-46133 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
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.
crypto-esnpmDescription
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. This is because it both (1) defaults to SHA1, a cryptographic hash algorithm considered insecure since at least 2005 and (2) 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. Remediation of this issue might be very difficult, as the changes required to fix this issue would change the output of this method and thus break most, if not all, current uses of this method as configured by default.
Potential Impact:
- If used to protect passwords, the impact is high.
- If used to generate signatures, the impact is high.
Probability / risk analysis / attack enumeration:
- For at most $45,000, 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.
- 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' or 'pepper' or any other secret unknown to the attacker. It will still create an identical signature.
crypto-js has 10,642 public users as displayed on NPM, today October 11th 2023. The number of transient dependents is likely several orders of magnitude higher.
A very rough GitHub search shows 432 files cross GitHub using PBKDF2 in crypto-js in Typescript or JavaScript, but not specifying any number of iterations.
Affected versions
All versions are impacted. This code has been the same since crypto-js was first created.
Further Cryptanalysis
The issue here is especially egregious because the length extension attack makes useless any secret that might be appended to the plaintext before calculating its signature.
Consider a scheme in which a secret is created for a user's username, and that secret is used to protect e.g. their passwords. Let's say that password is 'fake-password', and their username is 'example-username'.
To encrypt the user password via symmetric encryption we might do encrypt(plaintext: 'fake-password', encryption_key: cryptojs.pbkdf2(value: 'example username' + salt_or_pepper)). By this means, we would, in theory, create an encryption_key that can be determined from the public username, but which requires the secret salt_or_pepper to generate. This is a common scheme for protecting passwords, as exemplified in bcrypt & scrypt. Because the encryption key is symmetric, we can use this derived key to also decrypt the ciphertext.
Because of the length extension issue, if the attacker obtains (via attack 1), a collision with 'example username', the attacker does not need to know salt_or_pepper to decrypt their account data, only their public username.
Description
PBKDF2 is a key-derivation function that is used for two main purposes: (1) to stretch or squash a variable length password's entropy into a fixed size for consumption by another cryptographic operation and (2) to reduce the chance of downstream operations recovering the password input (for example, for password storage).
Unlike the modern webcrypto standard, crypto-js does not throw an error when a number of iterations is not specified, and defaults to one single iteration. In the year 1993, when PBKDF2 was originally specified, the minimum number of iterations suggested was set at 1,000. Today, OWASP recommends 1,300,000:
Workarounds
Consult the OWASP PBKDF2 Cheatsheet. Configure to use SHA256 with at least 250,000 iterations.
Coordinated disclosure
This issue was simultaneously submitted to crypto-js and crypto-es on the 23rd of October 2023.
Caveats
This issue was found in a security review that was not scoped to crypto-es. This report is not an indication that crypto-es has undergone a formal security assessment by the author.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | crypto-es | all versions | 2.1.0npm install crypto-es@2.1.0 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for crypto-es, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update crypto-es to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-46133 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-46133 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-46133. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-46133 in your dependencies?
O3 Security finds CVE-2023-46133 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.