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CVE-2026-63756

CRITICAL 9.2

Published 2026-07-20 · Last modified 2026-07-21

SurrealDB versions before 3.1.0 contain a time-of-check/time-of-use race condition in the HTTP /rpc endpoint that allows unauthenticated requests to inherit authenticated session state. Unauthenticated attackers can send concurrent requests to the /rpc endpoint while legitimate authenticated traffic is active to execute operations with hijacked user privileges.

ELEVATED IMPACT

Severe if exploited (CVSS 9.2), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.3%chance of exploitation in 30 days · 18th percentile

○ In CISA KEV ○ Public exploit / PoC

Impact if exploited

9.2CVSS 4.0 · 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
  • ⚠Requirements: Specific conditions must be present

✓ 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-2026-63756/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-2026-63756/poc.json

Affected

Vendors Surrealdb

Products Surrealdb

Weakness (CWE)

  • CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

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

All CVSS metrics

  • CRITICAL 9.2 v4.0 · CNA Primary
    CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
  • HIGH 8.1 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
  • CRITICAL 9.2 v4.0 · NVD Secondary
    CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/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
  • HIGH 8.1 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Advisories

Sources: NVD · CVE.org · EPSS