Authentication Bypass in joserfc (CVE-2026-49852)
Summary
Authentication bypass in joserfc (CVE-2026-49852). Risk of unauthorized operations or information disclosure. Exploitable via joserfc.jwt.decode. Mitigation: upgrade to 1.6.8 or later.
Original description
The description as published by the source.
joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to 1.6.8, joserfc.jwt.decode accepts attacker-forged HMAC-signed tokens when the caller-supplied verification key is the empty string or None, because HMACAlgorithm.sign and HMACAlgorithm.verify in src/joserfc/_rfc7518/jws_algs.py pass the output of OctKey.get_op_key(...) to hmac.new(...) and OctKey.import_key in src/joserfc/_rfc7518/oct_key.py only emits a SecurityWarning for keys shorter than 14 bytes without rejecting zero-length input. This issue is fixed in version 1.6.8.
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49852 has been found in joserfc.
Attackers can target a specific entry point like joserfc.jwt.decode over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade joserfc to 1.6.8 or later.
If unsure, ask your IT team or search "joserfc CVE-2026-49852" on the vendor's site.
CVE-2026-49852 (joserfc) — CWE-287
Attack surface: joserfc.jwt.decode / None / HMACAlgorithm.sign / HMACAlgorithm.verify
Patched: 1.6.8 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Authentication bypass (CWE-287) exists in joserfc. Attackers reach the vulnerable code path via joserfc.jwt.decode.
Check the vendor advisory for the affected versions of joserfc. Attack surface: joserfc.jwt.decode / None / HMACAlgorithm.sign / HMACAlgorithm.verify.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 1.6.8.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'joserfc' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'joserfc' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
joserfcを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade joserfc to 1.6.8ステージング環境で 1.6.8 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-49852 joserfc
- Ubuntu UBUNTU-CVE-2026-49852 joserfc
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- patch github.com
- web github.com
- web github.com
- web github.com