October 28, 2026

CVE Watchtower

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CVE-2026-56434NVD

Vulnerability Summary

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process.

Impact:
This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only.

Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Severity Level
MEDIUM(6.5)
Published Date
Jul 15, 2026
Last Modified
Jul 15, 2026
Exploitation Status
No confirmed exploitation yet
EPSS Score (30-Day)
0.45%Probability
Root Weakness (CWE)
CWE-416: Unknown/Unlisted Weakness ↗
Refer to the official MITRE database for detailed architectural specifications regarding this weakness.
CVSS v4.0 Base Metrics — Score 8.3 (HIGH)
Attack VectorNetwork
Attack ComplexityLow
Attack RequirementsPresent
Privileges RequiredNone
User InteractionNone
Confidentiality (Vulnerable System)None
Integrity (Vulnerable System)Low
Availability (Vulnerable System)High
Confidentiality (Subsequent System)None
Integrity (Subsequent System)None
Availability (Subsequent System)None
CVSS v3.1 Base Metrics — Score 6.5 (MEDIUM)
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone
User InteractionNone
ScopeUnchanged
ConfidentialityNone
IntegrityLow
AvailabilityHigh

Affected & Patched Versions

Affected Versions
  • F5 NGINX Plus >= 37.0.0.1 and < 37.0.3.1
  • F5 NGINX Plus >= R36 and < R36 P7
  • F5 NGINX Plus >= R33 and < *
  • F5 NGINX Open Source >= 1.31.2 and < 1.31.3
  • F5 NGINX Open Source >= 0.8.11 and < 1.30.4
Patched Versions
  • F5 NGINX Plus 37.0.3.1
  • F5 NGINX Plus R36 P7
  • F5 NGINX Plus *
  • F5 NGINX Open Source 1.31.3
  • F5 NGINX Open Source 1.30.4
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🎁7-Day Free Trial — Try Pro or Team, no card required.
📧Email Delivery — Threat intel straight to your inbox.
♾️Unlimited Vendors — Track your entire stack.
🚨All New CVEs — Be the first to know.
📈EPSS Spike Alerts — Catch rising risk before it peaks.
🎯Custom EPSS/CVSS — Filter noise, focus on risk.
🛡️Exploit Intel — A 2nd confirmed-exploit signal beyond KEV.
🐙GitHub Issues — Auto-tracked, no duplicates.
📬Weekly Digest — One clean summary, not inbox spam.
🏷️Watchlist Groups — Tag alerts by team (Infra/AppSec/SOC).
💬Webhooks — Slack & Teams integration.
🔀Smart Routing — Critical alerts to one channel, rest to another.
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External References