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CVE-2026-65624: Cowboy HTTP/1.1 max_headers Bypass via Duplicate Header Names Enables Memory Exhaustion

CVE-2026-65624 is a vulnerability in Cowboy HTTP/1.1 max_headers Bypass via Duplicate Header Names Enables Memory Exhaustion, rated Moderate by Microsoft. Microsoft has not reported exploitation in the wild. The EPSS model estimates a 0.38% probability of exploitation activity in the next 30 days, higher than 33% of all scored vulnerabilities. Microsoft released the fix on 6 August 2026, outside Patch Tuesday. It affects 2 products in 1 product family (Open Source Software).

Key facts

CVE ID
CVE-2026-65624
Severity
N/A
Microsoft severity
Moderate
Exploited in the wild
No
Publicly disclosed
No
Weakness
CWE-770
EPSS
0.38% (percentile 33%)
CISA KEV
Not listed
Released
Last updated
Patch Tuesday
July 2026 Patch Tuesday
Product families
Open Source Software

Affected products (2)

Open Source Software

ProductSecurity updateTypeFixed buildRestart
azl3 rabbitmq-server 3.13.7-8 on Azure Linux 3.0Security updateSecurity Update3.13.7-9
azl3 rabbitmq-server 3.13.7-9 on Azure Linux 3.0Security updateSecurity Update3.13.7-9

NIST NVD data

NVD status
Deferred
NVD CVSS
6.9 (MEDIUM)
NVD weakness
CWE-770
Published to NVD
NVD last modified

References

Revision history

VersionDateDescription
1.0Information published.
2.0Information published.
3.0Information published.
4.0Information published.

Sources