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CVE-2026-40986

MEDIUM 4.8

Published 2026-06-11 · Last modified 2026-06-23

Spring Web Flow's JavaScript RemotingHandler renders the body of an error response as HTML even when the response is not "text/html", which can result in a scripting attack in the user's browser if the error response from the server contains error details with input reflected from an attacker. Affected versions: Spring Web Flow 4.0.0; 3.0.0 through 3.0.1; 2.5.0 through 2.5.1.

NO EXPLOITATION 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 · 10th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

4.8CVSS 3.1 · MEDIUM

  • ConfidentialityNone
  • IntegrityHigh
  • AvailabilityNone

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ⚠Privileges: Requires a low-privilege account
  • ⚠User interaction: A user must take an action (click / open a file)
  • ⚠Complexity: Needs a race window or specific setup

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept & exploit code

Test against your own equipment

curl -s https://vulnpedia.com/cve/CVE-2026-40986/poc.jsonMachine-readable PoC index for this CVE (for automation).

Listed for defensive triage, patch verification, and authorized testing on systems you own. Machine-readable: /cve/CVE-2026-40986/poc.json

Affected

Vendors Spring

Products Spring Web Flow

Weakness (CWE)

  • CWE-79: : Improper Neutralization of Input During Web Page Generation (Cross-site Scripting)

CVSS vector

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

All CVSS metrics

  • MEDIUM 4.8 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N
  • MEDIUM 4.8 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:H/A:N

References

Technical & other

Sources: NVD · CVE.org · EPSS