CVE-2026-49289Network attack vector

Unauthenticated service interrupt via XPath transforms

Published Aug 19, 2026 · Updated Aug 19, 2026

Denial of service in SimpleSAMLphp SAML2 4.19.2 and 4.20.2 allows remote attackers to stall SAML processing via crafted signed messages. During XML signature validation in src/SAML2/Utils.php, the library accepts attacker-chosen ds:Transform elements and can evaluate XPath-based transforms instead of limiting SignedInfo references to the SAML profile's allowed canonicalization and enveloped-signature algorithms. Any deployment that verifies untrusted SAML assertions or responses with the affected library is exposed, and the bounded impact is service interruption from excessive processing rather than message forgery or data disclosure.

CVSS severity7.5
High
EPSS probability0.56%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in SimpleSAMLphp SAML2 4.19.2 and 4.20.2 allows remote attackers to stall SAML processing via crafted signed messages. During XML signature validation in src/SAML2/Utils.php, the library accepts attacker-chosen ds:Transform elements and can evaluate XPath-based transforms instead of limiting SignedInfo references to the SAML profile's allowed canonicalization and enveloped-signature algorithms. Any deployment that verifies untrusted SAML assertions or responses with the affected library is exposed, and the bounded impact is service interruption from excessive processing rather than message forgery or data disclosure.

The record

CVE
CVE-2026-49289
Published
Aug 19, 2026
Updated
Aug 19, 2026
Vendor
SimpleSAMLphp
Product
SAML2
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>= 4.19.2, < 4.19.3
  2. Affected versionversion=>= 4.20.2, < 4.20.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SimpleSAMLphp · SAML2version=>= 4.19.2, < 4.19.3; version=>= 4.20.2, < 4.20.3

Published CVSS scores

7.5GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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