Security readout for executives and security teams
Plain-English summary
Samly does not ensure that a SAML login assertion is used only once. Anyone who captures a valid assertion may reuse it until it expires, repeatedly creating sessions as that user. Captured assertions may come from network traffic, browser history, or logs, making privileged-account exposure especially serious.
Executive priority
Treat as an urgent identity-security issue wherever Samly protects sensitive or privileged access. Prioritize exposure inventory, removal of assertion material from logs, and monitoring for replay while awaiting or applying authoritative project remediation.
Technical view
Samly.Helper.decode_idp_auth_resp/3 calls esaml_sp:validate_assertion/2, whose default duplicate detector performs no check. Samly does not expose esaml’s duplicate-detection callback, leaving SAML bearer assertions replayable until NotOnOrAfter. The bundle describes Samly 0.3.0 onward as affected, although its structured version entries contain conflicting default-status data.
Likely exposure
Applications using Dropbox Samly 0.3.0 or later for SAML Web Browser SSO may be exposed. Practical compromise requires access to a still-valid SAMLResponse, so environments that log assertions, expose browser artifacts, or inadequately protect authentication traffic face greater risk.
Exploitation context
The CVSS 4.0 score is 9.1, reflecting remote, low-complexity authentication bypass after an assertion is captured. The bundle does not report CISA KEV inclusion or provide evidence of active exploitation. Replay remains limited by the assertion’s NotOnOrAfter timestamp.
Researcher notes
The core weakness is CWE-294 capture-replay caused by absent duplicate detection, not signature forgery. Identical assertion bytes can establish multiple sessions during their validity window. The supplied affected-version structures conflict with the narrative statement, and no fixed version or confirmed vendor mitigation appears in the bundle.
Mitigation direction
- Check Samly and ERLEF guidance for an official fixed release or supported duplicate-detection configuration.
- Upgrade promptly when the project identifies a corrected version.
- Prevent SAMLResponse values from entering application, proxy, tracing, or analytics logs.
- Restrict access to existing logs and browser artifacts that may contain assertions.
- Consider shorter assertion lifetimes as a temporary control; this does not prevent replay.
Validation and detection
- Inventory applications and dependency locks for Samly versions from 0.3.0 onward.
- Confirm whether authentication reaches Samly.Helper.decode_idp_auth_resp/3 and esaml_sp:validate_assertion/2.
- Review logging and tracing configurations for storage of SAMLResponse values.
- Investigate repeated use of identical assertion identifiers or safely computed response fingerprints.
- After remediation, verify one-time-use enforcement through authorized non-production authentication testing.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-294: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-53424 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.1 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N——EEFVulnerability scoring details
Base CVSS 4.0 score
9.1CriticalVector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://cna.erlef.org/cves/CVE-2026-53424.htmlCVE reference, EEF · related, third-party-advisory
- https://osv.dev/vulnerability/EEF-CVE-2026-53424CVE reference, EEF · related
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Authentication Bypass by Capture-replay
Authentication Bypass by Capture-replay represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.