Skip to content
Fencer Intel
medium 5.3

CVE-2026-48990 json

joserfc: b64=false RFC7797 JWS payloads bypass JWSRegistry payload-size limits during deserialization

published 5mo ago modified 16d ago also EUVD-2026-37805 , GHSA-wphv-vfrh-23q5 , PYSEC-2026-2530

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 14%
public exploits
0
none known

Summary

joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. In versions 1.3.4 through 1.6.5, joserfc accepts oversized RFC7797 b64=false JWS payloads without applying JWSRegistry.max_payload_length, which can lead to resource exhaustion. The normal JWS compact and flattened JSON paths reject payloads above the configured payload-size limit with ExceededSizeError. The RFC7797 unencoded payload paths do not make the same check. A valid b64=false compact or flattened JSON JWS can therefore deserialize successfully with a payload larger than JWSRegistry.max_payload_length. Applications that accept lower-trust JWS values and rely on joserfc to reject oversized token content during verification have a moderate availability risk. This issue has been fixed in version 1.6.7.

Patch / fix

  • pypi joserfc 1.6.7
  • hsiaoming joserfc 1.6.7
  • joserfc Debian 14 1.6.8-1

debian advisories DEBIAN-CVE-2026-48990

  • jaeger hummingbird 1 2.19.0-1.hum1

red hat advisories RHSA-2026:25039

  • python-joserfc openSUSE Tumbleweed 1.7.1-1.1

opensuse advisories openSUSE-SU-2026:11067-1

Is CVE-2026-48990 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-48990 updated cvss 5.3

joserfc: joserfc: Resource exhaustion via oversized JSON Web Signature (JWS) payloads

  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/lightspeed-chatbot-rhel9 1785646188
    fixed: vendor fix “The risk can be mitigated by rejecting oversized serialized JWS inputs before they reach joserfc and enforcing strict request/body size limits at the application or reverse-proxy layer.” RHSA-2026:50479
  • Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/lightspeed-chatbot-rhel9 1785426734
    fixed: vendor fix “The risk can be mitigated by rejecting oversized serialized JWS inputs before they reach joserfc and enforcing strict request/body size limits at the application or reverse-proxy layer.” RHSA-2026:50340
  • Red Hat Hardened Images jaeger 2.19.0-1.hum1
    fixed: vendor fix “The risk can be mitigated by rejecting oversized serialized JWS inputs before they reach joserfc and enforcing strict request/body size limits at the application or reverse-proxy layer.” RHSA-2026:25039
  • Red Hat Migration Toolkit for Applications 8.2 mta/mta-solution-server-rhel9 1784109883
    fixed: vendor fix “The risk can be mitigated by rejecting oversized serialized JWS inputs before they reach joserfc and enforcing strict request/body size limits at the application or reverse-proxy layer.” RHSA-2026:43038
  • Red Hat Ansible Automation Platform 2.6 ansible-automation-platform-26/hub-rhel9 1785753568, ansible-automation-platform-26/gateway-rhel9 1785780020, ansible-automation-platform-26/hub-web-rhel9 1785756951, ansible-automation-platform-26/receptor-rhel9 1785632117, ansible-automation-platform-26/mcp-tools-rhel9 1785633968, ansible-automation-platform-26/controller-rhel9 1785753810, +24 more Red Hat Ansible Automation Platform 2.7 ansible-automation-platform-27/hub-rhel9 1785376164, ansible-automation-platform-27/gateway-rhel9 1785435970, ansible-automation-platform-27/hub-web-rhel9 1785379466, ansible-automation-platform-27/receptor-rhel9 1785389482, ansible-automation-platform-27/mcp-tools-rhel9 1785374970, ansible-automation-platform-27/controller-rhel9 1785378052, +25 more Red Hat Migration Toolkit for Applications 8.2 mta/mta-ui-rhel9 1783962515, mta/mta-cli-rhel9 1784211378, mta/mta-hub-rhel9 1784059743, mta/mta-rhel9-operator 1784219586, mta/mta-operator-bundle 1784220119, mta/mta-analyzer-addon-rhel9 1784163267, +7 more Red Hat Satellite 6 satellite/foreman-mcp-server-rhel9
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
4mo ago

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 14% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/authlib/joserfc/security/advisories/GHSA-wphv-vfrh-23q5 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
GitHub 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
OSV 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
pypi joserfc
>=1.3.4, <1.6.7
1.6.7

Affected products

  • authlib joserfc

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption
  • CWE-770 Allocation of Resources Without Limits or Throttling

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of authlib/joserfc published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.