CVE-2022-35507Public exploitNetwork attack vector

Client-side denial of service via CR-only header injection

Published Dec 4, 2022 · Updated Apr 24, 2025

Response-header CRLF injection in Proxmox VE and Mail Gateway allows remote attackers to block a victim's web-interface access. PVE::APIServer::AnyEvent copies an error message into the HTTP status line after a regex removes LF but permits a CR character, enabling an injected Set-Cookie header. Exploitation requires a Chromium-based browser that accepts CR-only header breaks and permits third-party cookies; oversized cookies then make that browser's requests exceed the server's 8,192-byte header limit until the cookies are cleared.

CVSS severity7.1
High
EPSS probability1.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Response-header CRLF injection in Proxmox VE and Mail Gateway allows remote attackers to block a victim's web-interface access. PVE::APIServer::AnyEvent copies an error message into the HTTP status line after a regex removes LF but permits a CR character, enabling an injected Set-Cookie header. Exploitation requires a Chromium-based browser that accepts CR-only header breaks and permits third-party cookies; oversized cookies then make that browser's requests exceed the server's 8,192-byte header limit until the cookies are cleared.

The record

CVE
CVE-2022-35507
Published
Dec 4, 2022
Updated
Apr 24, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-74, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 4, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:H
4.3CISA ADP VulnrichmentCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-74Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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