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Uncontrolled Resource ConsumptionWeakness · CWE-400

CVE-2026-49289

HIGH · 7.5 CVSS v3.1 Published 2026-08-19
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click Patch available 6 days old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
The SimpleSAMLphp SAML2 library is a PHP library for SAML2 related functionality. In 4.19.2 and 4.20.2, the library permits attacker-controlled XPath transforms while processing XML signatures in specially crafted SAML messages. XPath evaluation can consume uncontrolled processing resources, allowing a remote unauthenticated attacker to deny service to any entity relying on SimpleSAMLphp or directly on the SAML2 library. The mitigation limits the number of transforms, permits only transform algorithms identified by the SAML 2.0 Core specification, and specifically rejects XPath transforms. This issue is fixed in versions 4.19.3 and 4.20.3.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-400

A single request can consume unbounded CPU, memory, or connections, so a modest amount of malicious traffic exhausts the service. The result is denial of service for everyone else. Remediation is enforcing limits, quotas, and timeouts on what any one request can use.

General guidance for the uncontrolled resource consumption class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix High confidence

4.19.3 or 4.20.3 (latest stable)

  1. Identify the SimpleSAMLphp SAML2 library in your project (commonly via composer.json as 'simplesamlphp/saml2')
  2. Run 'composer show simplesamlphp/saml2' to confirm the currently installed version
  3. If version is 4.19.2 or 4.20.2, run 'composer require simplesamlphp/saml2:4.19.3 --no-interaction' or 'composer require simplesamlphp/saml2:4.20.3 --no-interaction' to upgrade
  4. Verify the upgrade completed successfully with 'composer show simplesamlphp/saml2'
  5. Run your project's test suite to confirm the upgrade does not break functionality
  6. Deploy the updated package to your environment
Caveat No breaking changes expected; the fix adds validation and rejection of XPath transforms per SAML 2.0 Core spec

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-49289 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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