CVE-2026-49283: simplesamlphp saml2 · Improper Certificate Validation
Affects simplesamlphp saml2Source CVE Database V5
Not known to be exploited · CVSS 8.7 High · fixed in 6.2.1 : patch simplesamlphp saml2 soon.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-08-19.
- Patch
- Available – fixed in 6.2.1, 5.0.6, 4.20.2 +1
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:NExploitation evidence
Disclosed: evidence found.
CVE published 19 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade simplesamlphp saml2 to 6.2.1, 5.0.6, 4.20.2 or 4.19.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| simplesamlphpsaml2 | Affected
| Fixed in
|
| simplesamlphpsaml2 | Affected
| Fixed in
|
| simplesamlphpsaml2 | Affected
| Fixed in
|
| simplesamlphpsaml2 | Affected
| Fixed in
|
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.
References
- github.com/simplesamlphp/saml2/security/advisories/GHSA-6929-8p9f-26jx (opens in a new tab)
- github.com/simplesamlphp/saml2/commit/4a71b20d8d845579fd0a54d6449c265b40db459d (opens in a new tab)
- github.com/simplesamlphp/saml2/commit/a2c1ac588c70d7b7998546cf32675fb113f22a5f (opens in a new tab)
- github.com/simplesamlphp/saml2/commit/d5c213132ef671c0018a11252322034dbddd735a (opens in a new tab)
- github.com/simplesamlphp/saml2/commit/e2df7992609964951b2a3e7d6566b7427b2a968f (opens in a new tab)