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CVE-2026-18937

CRITICAL 9 PoC AVAILABLE

Published 2026-08-19 · Last modified 2026-08-19

The Broken Link Checker WordPress plugin before 2.4.12 does not limit which query variables it accepts from user input on sites using plain permalinks, allowing unauthenticated users to overwrite arbitrary PHP global variables, and to execute arbitrary code on the server when a classic (non-block) is active.

EXPLOIT AVAILABLE

Public exploit or PoC code exists. Modeled probability is still low, but the barrier to attack is reduced — watch closely.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 33rd percentile

○ In CISA KEV ● Public exploit / PoC

Impact if exploited

9CVSS 3.1 · CRITICAL

  • ConfidentialityHigh
  • IntegrityHigh
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ⚠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-2026-18937/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-2026-18937/poc.json

Affected

Vendors Unknown

Products Broken Link Checker

Weakness (CWE)

  • CWE-94: Improper Control of Generation of Code ('Code Injection')

CVSS vector

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

All CVSS metrics

  • CRITICAL 9 v3.1 · ADP Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
  • CRITICAL 9 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

References

Exploits & PoC

Sources: NVD · CVE.org · EPSS