CVE-2026-49283
No exploitation reported by the sources we read.
- Published2026-08-19
- Fixed in6.2.1 · 5.0.6 · 4.20.2 · 4.19.3
- WeaknessCWE-295
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
Description
The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. Prior to versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1, the HTTPArtifact::receive() flow can treat an unsigned embedded SAML Response as cryptographically valid for the wrong identity provider. SOAPClient::addSSLValidator() attaches a TLS-based validator to the outer SOAP ArtifactResponse, while the embedded Response receives a validator that delegates to the outer message and is later checked against metadata selected from the embedded response issuer rather than necessarily the artifact issuer. SOAPClient::validateSSL() returns normally when the TLS public key does not match the key being validated, and SAML2\Message::validate() treats a validator call that does not throw as successful. In a multi-IdP federation, a malicious or lower-trust IdP can therefore provide an ArtifactResponse containing an unsigned Response that claims a higher-trust victim IdP as issuer and authenticate as arbitrary users with attacker-chosen assertion attributes, NameID, and session data. This issue is fixed in versions 4.19.3, 4.20.2, 5.0.6, and 6.2.1.
Timeline
dates in UTC- 2026-08-1915:17CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-49283?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-49283?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
OSV| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 6.x | ≥ 6.0.0, < 6.2.1 | 6.2.1 | OSV |
| 5.0 | ≥ 5.0.0, < 5.0.6 | 5.0.6 | OSV |
| 4.20 | ≥ 4.20.0, < 4.20.2 | 4.20.2 | OSV |
| 4.19 | < 4.19.3 | 4.19.3 | OSV |
| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 4.20 | ≥ 4.20.0, < 4.20.2 | 4.20.2 | OSV |
| 4.19 | < 4.19.3 | 4.19.3 | OSV |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
- Update simplesamlphp/saml2 to 6.2.1 · 5.0.6 · 4.20.2 · 4.19.3
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:N
- Published
- 2026-08-19
- Last Modified
- 2026-09-18
- NVD status
- Deferred
Frequently asked questions
What is CVE-2026-49283?
Is CVE-2026-49283 actively exploited?
What is the CVSS score for CVE-2026-49283?
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