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TI-2026-38506 Aliases CVE-2026-53424GHSA-5x87-gf34-8ww7

Missing one-time-use enforcement in Samly allows replay of SAML bearer assertions

Priority MEDIUM 48CWE-294Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
High · High · None
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-294.

Summary

Authentication Bypass by Capture-replay vulnerability in dropbox samly allows an attacker to authenticate as the subject of a captured SAML assertion by resubmitting it. Samly.Helper.decode_idp_auth_resp/3 in lib/samly/helper.ex calls esaml_sp:validate_assertion/2, whose default duplicate detector is a no-op. The /3 arity accepting a DuplicateFun exists in esaml and implements the check, but Samly never calls it and offers no configuration to supply one, so the SAML 2.0 Web Browser SSO Profile requirement that a bearer assertion be used once is unenforced. An attacker holding a valid SAMLResponse obtained from the network, from browser history, or from logs can submit the identical bytes repeatedly until the assertion's NotOnOrAfter passes, each time establishing a session as the assertion's subject. This issue affects samly: from 0.3.0 onward.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00602 49th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
dropboxsamly0.3.0 and later—No fix listedCNA
  • samly Vendordropbox Affected 0.3.0 and later Fixed in — No fix listed CNA

CPE names CNA · 2

CPEVersionsRoleVendor
cpe:2.3:a:dropbox:samly:*:*:*:*:*:*:*:*——dropbox
cpe:2.3:a:handnot2:samly:*:*:*:*:*:*:*:*——handnot2
  • cpe:2.3:a:dropbox:samly:*:*:*:*:*:*:*:* Versions — — ·dropbox
  • cpe:2.3:a:handnot2:samly:*:*:*:*:*:*:*:* Versions — — ·handnot2

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-53424
  2. 2026-10-03 Alias added: GHSA-5x87-gf34-8ww7

References

Advisory 1

Other 1

  • TI-2026-79218 Unbounded SAML message decompression in esaml allows memory exhaustion CVSS 4.0HIGH 8.7
  • TI-2026-79203 Unbounded atom creation in esaml SAML parsing crashes Erlang nodes CVSS 4.0HIGH 8.7
  • TI-2026-79217 Unbounded atom creation from unsigned LogoutResponse status codes in esaml allows atom table exhaustion CVSS 4.0HIGH 8.2
  • TI-2024-16922 In the Samly package before 1.4.0 for Elixir, Samly.State.Store.get_assertion/3 can… CVSS 3.1CRITICAL 9.8
  • TI-2024-05491 Protection mechanism failure in Dropbox Desktop CVSS 3.1HIGH 8.8
  • TI-2022-04364 Dropbox merou SSH Public Key public_key.py add_public_key injection CVSS 3.1CRITICAL 9.8
See all 21 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences