VulnerabilityPublished 11 Jun 2025

CVE-2025-4673: Go standard library net/http · Insertion of Sensitive Information Into Sent Data

Affects Go standard library net/httpSource CVE Database V5

Not known to be exploited · CVSS 6.8 Medium.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

6.8Medium

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: None
Availability: None

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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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.

What to do

Affected software

Product	Affected	Fixed in
Gonet/http`pkg:golang/net/http`Other threats	Affected =0 =1.24.0-0	Fixed in–

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

AI-suggested

To mitigate CVE-2025-4673, European organizations should take immediate steps beyond generic patching advice: 1) Monitor for updates from the Go project and prioritize upgrading the net/http package to a fixed version once available. 2) Audit all Go-based applications and services that use the net/http package, focusing on those that handle proxy authentication and perform HTTP redirects, to identify potential exposure. 3) Implement strict validation and sanitization of HTTP headers during redirects, ensuring that Proxy-Authorization and Proxy-Authenticate headers are not forwarded to different origins. 4) Where feasible, configure proxies and HTTP clients to avoid sending sensitive proxy headers on cross-origin redirects or disable automatic redirect following in sensitive contexts. 5) Employ network-level controls to restrict outbound traffic from servers handling proxy credentials to only trusted destinations, reducing the risk of credential leakage to untrusted endpoints. 6) Enhance logging and monitoring to detect unusual redirect patterns or unexpected outbound requests containing proxy headers. 7) Educate developers and DevOps teams about this vulnerability to ensure secure coding practices around HTTP header management and redirect handling. These targeted mitigations will help reduce the risk until patches are applied and prevent exploitation in complex proxy environments.

Description

Proxy-Authorization and Proxy-Authenticate headers persisted on cross-origin redirects potentially leaking sensitive information.

Impact

For European organizations, the impact of CVE-2025-4673 can be considerable, especially for those relying on Go-based infrastructure components such as web servers, reverse proxies, or microservices that handle HTTP traffic with proxy authentication. The leakage of Proxy-Authorization headers during cross-origin redirects could expose sensitive proxy credentials to malicious external servers, potentially allowing attackers to misuse proxy access, intercept or manipulate traffic, or gain unauthorized network access. This could lead to confidentiality breaches, especially in environments where proxy authentication is used to control access to internal or external resources. Given the medium severity and the high confidentiality impact, organizations handling sensitive data, including financial institutions, healthcare providers, and government agencies in Europe, could face data exposure risks. Additionally, the vulnerability could be leveraged as part of a larger attack chain to pivot within networks or exfiltrate data. The fact that exploitation does not require authentication or user interaction increases the risk profile, although the high attack complexity somewhat limits widespread exploitation. However, organizations with complex proxy configurations or those that rely heavily on automated HTTP client libraries in Go are at higher risk. The vulnerability also poses compliance risks under GDPR and other European data protection regulations if sensitive information is leaked due to this flaw.

CWE-201Insertion of Sensitive Information Into Sent Data (opens in a new tab)
Base weaknessOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.
Requirements
Specify which data in the software should be regarded as sensitive. Consider which types of users should have access to which types of data.
Implementation
Ensure that any possibly sensitive data specified in the requirements is verified with designers to ensure that it is either a calculated risk or mitigated elsewhere.
System Configuration
Setup default error messages so that unexpected errors do not disclose sensitive information.
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
Choosing Message Identifier (opens in a new tab)
Exploiting Incorrectly Configured SSL/TLS (opens in a new tab)
WiFi MAC Address Tracking (opens in a new tab)
WiFi SSID Tracking (opens in a new tab)
Cellular Broadcast Message Request (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 12 Jul 2025, 08:46 UTC

WeaknessesCWE-201

Technical details

References

Community reviews

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