VulnerabilityPublished 30 Oct 2025Updated 5 Nov 2025

CVE-2025-58186: Despite HTTP headers having a default limit of 1MB, the number of cookies that can be parsed does not

Source GCVE Database

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Authoritative record:CVE-2025-58186· Medium 5.3

Not known to be exploited · CVSS 5.3 Medium.

Data as of 4 Nov 2026, 18:00 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 29 Oct 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-rjcg-56ph-3qvg

What to do

Affected software

Product	Affected	Fixed in
Gonet/http`pkg:golang/net/http`Other threats	Affected =0 =1.25.0	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until a fix is available, consider implementing limits on the number of cookies parsed or applying rate limiting and request size restrictions at the network or application level to mitigate potential exploitation.

Description

CVE-2025-58186 is a vulnerability where an HTTP server does not limit the number of cookies parsed, despite HTTP headers having a default size limit of 1MB. An attacker can exploit this by sending many small cookies, causing excessive memory allocation on the server and resulting in large memory consumption.

Impact

The impact is limited to availability degradation caused by excessive memory consumption on the HTTP server. There is no confidentiality or integrity impact reported. The vulnerability could be exploited remotely without privileges or user interaction, making it a potential denial-of-service vector through resource exhaustion.

Summary

This vulnerability arises because the HTTP server enforces a 1MB limit on the total size of HTTP headers but does not impose a limit on the number of cookies parsed within those headers. By sending numerous very small cookies (e.g., "a=;"), an attacker can cause the server to allocate a large number of internal data structures, leading to significant memory consumption. This can degrade server performance or potentially cause denial of service due to resource exhaustion. The CVSS 3.1 base score is 5.3, reflecting a medium severity impact with no confidentiality or integrity loss but availability impact due to resource exhaustion.

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