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.
Blast Radius
pyjwtReal-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
Summary
The wrong string if check is run for iss checking, resulting in "acb" being accepted for "_abc_".
Details
This is a bug introduced in version 2.10.0: checking the "iss" claim
changed from isinstance(issuer, list) to isinstance(issuer, Sequence).
- if isinstance(issuer, list):
+ if isinstance(issuer, Sequence):
if payload["iss"] not in issuer:
raise InvalidIssuerError("Invalid issuer")
else:
Since str is a Sequnce, but not a list, in is also used for string
comparison. This results in if "abc" not in "__abcd__": being
checked instead of if "abc" != "__abc__":.
PoC
Check out the unit tests added here: https://github.com/jpadilla/pyjwt-ghsa-75c5-xw7c-p5pm
issuer = "urn:expected"
payload = {"iss": "urn:"}
token = jwt.encode(payload, "secret")
# decode() succeeds, even though `"urn:" != "urn:expected". No exception is raised.
with pytest.raises(InvalidIssuerError):
jwt.decode(token, "secret", issuer=issuer, algorithms=["HS256"])
Impact
I would say the real world impact is not that high, seeing as the signature still has to match. We should still fix it.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pyjwt | ≥ 2.10.0&&< 2.10.1 | 2.10.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyjwt. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update pyjwt to 2.10.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-75c5-xw7c-p5pm 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 pinpoints whether GHSA-75c5-xw7c-p5pm is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-75c5-xw7c-p5pm. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-75c5-xw7c-p5pm in your dependencies?
O3 detects GHSA-75c5-xw7c-p5pm across PyPI dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.