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TI-2025-33087 Aliases CVE-2025-53094

ESPAsyncWebServer Vulnerable to CRLF Injection in AsyncWebHeader.cpp

Priority HIGH 77CWE-113Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

ESPAsyncWebServer is an asynchronous HTTP and WebSocket server library for ESP32, ESP8266, RP2040 and RP2350. In versions up to and including 3.7.8, a CRLF (Carriage Return Line Feed) injection vulnerability exists in the construction and output of HTTP headers within `AsyncWebHeader.cpp`. Unsanitized input allows attackers to inject CR (`\r`) or LF (`\n`) characters into header names or values, leading to arbitrary header or response manipulation. Manipulation of HTTP headers and responses can enable a wide range of attacks, making the severity of this vulnerability high. A fix is available at pull request 211 and is expected to be part of version 3.7.9.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.0043 37th percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
ESP32AsyncESPAsyncWebServerup to 3.7.8—No fix listedCNA
  • ESPAsyncWebServer VendorESP32Async Affected up to 3.7.8 Fixed in — No fix listed CNA

Remediation

No fixed version listed by the sources yet.

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-53094

References

Other 3

  • TI-2026-39406 ESPAsyncWebServer: Integer overflow in multipart boundary parser causes denial of service CVSS 4.0HIGH 8.7
  • TI-2026-83405 NULL pointer write in ESPAsyncWebServer multipart parser CVSS 3.1HIGH 7.5

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences