CVE-2026-18709
MEDIUM 5.9An issue in MongoDB Server could allow an authenticated user with direct network access to a shard to improperly commit or abort an in-progress prepared transaction, bypassing the intended transaction coordination process. This could result in cross-shard data inconsistency, cluster clock corruption, and violation of transaction atomicity guarantees.
No known exploitation, public exploit, or elevated probability at this time. Track for changes.
Exploitation likelihood
0.1%chance of exploitation in 30 days · 4th percentile
Impact if exploited
5.9CVSS 4.0 · MEDIUM
- ConfidentialityNone
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ⚠Access: Must sit on the same / adjacent network
- ⚠Privileges: Requires a low-privilege account
- ✓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
- github-search Search GitHub for public PoC repos
Test against your own equipment
curl -s https://vulnpedia.com/cve/CVE-2026-18709/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-2026-18709/poc.json
Weakness (CWE)
- CWE-862: : Missing Authorization
CVSS vector
CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
All CVSS metrics
- MEDIUM 5.9 v4.0 · CNA Primary
CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N - MEDIUM 6.4 v3.1 · CNA Primary
CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H - MEDIUM 5.9 v4.0 · NVD Secondary
CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:N/VC:N/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 - MEDIUM 6.4 v3.1 · NVD Secondary
CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H