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CVE-2026-91857

MEDIUM 5.3 ALL-YEARS

Published 2026-09-15 · Last modified 2026-09-15 · CIRCL · NVD: Deferred

Affected versions of MISP expose several state-changing controller actions without restricting them to POST. The affected actions are:  - EventReportsController::purgeUnusedPictures()  - NoticelistsController::enableNoticelist()  - ServersController::removeOrphanedCorrelations()  - WorkflowsController::rebuildRedis() The patch adds allowMethod(['post']) to each action, preventing them from being triggered through ordinary GET requests. For purgeUnusedPictures(), the corresponding UI previously used $.get(). The fix converts that request to POST and supplies X-CSRF-Token, while the controller enables header-only CSRF validation for that AJAX action. Because GET requests can be induced cross-origin through links, images, redirects, or navigation, accepting GET for these state-changing operations can let an attacker trigger them using the authenticated victim's session. Version affected: ≤2.5.45

LIMITED SIGNALS

No known exploitation, public exploit, or elevated probability at this time. Track for changes.

Exploitation likelihood

0.2%chance of exploitation in 30 days · 11th percentile

○ In CISA KEV○ Public exploit / PoC◆ SSVC: exploitation none, automatable no

Impact if exploited

5.3CVSS 4.0 · MEDIUM · CNA

  • ConfidentialityNone
  • IntegrityLow
  • AvailabilityLow

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ⚠User interaction: Succeeds with passive user activity
  • ✓Complexity: No special conditions — reliably repeatable
  • ✓Requirements: No special attack requirements

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

No public exploit or proof-of-concept code is catalogued for this CVE (no ExploitDB, Nuclei, or CISA-KEV entry). It may still exist — search GitHub or check the references below.

Affected

Vendors Misp

Products Misp

Weakness (CWE)

  • CWE-352: Cross-Site Request Forgery (CSRF)

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

All CVSS metrics

  • MEDIUM 5.3 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
  • MEDIUM 5.3 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

References

Patches & mitigations

Sources: NVD · CVE.org · EPSS