CVE-2025-61728VulnerabilityPublished 28 Jan 2026

CVE-2025-61728: Go standard library archive/zip · Inefficient Algorithmic Complexity

Affects Go standard library archive/zipSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 1.25.6 or 1.24.12 when convenient.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.25.6, 1.24.12

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

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

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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Jan 2026
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 2026-10-26.

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 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

Upgrade Go standard library archive/zip to 1.25.6 or 1.24.12.

Affected software

Product	Affected	Fixed in
Go standard libraryarchive/zip	Affected <1.24.12 >=1.25.0 <1.25.6	Fixed in 1.25.6 1.24.12
Goarchive/zip`pkg:golang/archive/zip`Other threats	Affected <1.24.12 >=1.25.0 <1.25.6	Fixed in 1.24.12 1.25.6
Gogithub.com/golang/go/archive/zip`pkg:golang/github.com/golang/go/archive/zip`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

1. Avoid processing ZIP archives from untrusted or unauthenticated sources, especially in automated workflows. 2. Implement strict resource limits (CPU time, memory usage) on processes handling ZIP files to prevent resource exhaustion. 3. Employ sandboxing or containerization for ZIP processing components to isolate potential DoS effects. 4. Monitor system and application logs for unusual CPU spikes or performance degradation during ZIP file handling. 5. Educate users and administrators about the risks of opening ZIP files from unknown origins to reduce user interaction exploitation. 6. Track Go project updates and apply patches promptly once available. 7. Consider alternative ZIP processing libraries or tools with known resistance to algorithmic complexity attacks if immediate patching is not feasible. 8. Integrate ZIP file scanning with security tools that can detect malformed or suspicious archive structures. 9. For critical systems, implement fallback mechanisms to maintain service availability if ZIP processing fails or is delayed. 10. Conduct regular security assessments and code reviews of applications using the Go archive/zip package to identify and mitigate potential abuse scenarios.

Description

CVE-2025-61728 is a medium severity vulnerability in the Go standard library's archive/zip package, caused by an inefficient super-linear file name indexing algorithm. When a file in a ZIP archive is opened for the first time, this algorithm is triggered, which can be exploited by a maliciously crafted ZIP archive to cause a denial of service (DoS) by consuming excessive CPU resources. The vulnerability affects all versions up to and including Go 1.25.0. Exploitation requires no privileges but does require user interaction to open a ZIP file. There are no known exploits in the wild yet, and no patches have been published at the time of this report. European organizations using Go for processing ZIP archives in network-facing or user-facing applications are at risk of service disruption. Mitigation involves avoiding untrusted ZIP files, implementing resource limits on ZIP processing, and monitoring for abnormal CPU usage. Countries with significant software development industries and critical infrastructure relying on Go, such as Germany, France, and the UK, are more likely to be impacted.

Impact

For European organizations, the primary impact of CVE-2025-61728 is the risk of denial of service through resource exhaustion when processing malicious ZIP archives. This can disrupt critical services, especially those that automatically handle ZIP files, such as cloud platforms, software build systems, and document management solutions. Organizations relying on Go-based applications in sectors like finance, healthcare, government, and telecommunications could face operational interruptions. The availability impact could cascade into financial losses, reputational damage, and compliance issues under regulations like GDPR if service disruptions affect customer data access. Since exploitation requires user interaction, phishing or social engineering could be vectors to deliver malicious ZIP files. The lack of known exploits currently reduces immediate risk but does not eliminate the threat, especially as attackers often weaponize such vulnerabilities post-disclosure. The absence of patches means organizations must rely on mitigations and monitoring until official fixes are released. Given the widespread use of Go in modern software stacks, the scope of affected systems is broad, increasing the potential impact across multiple industries in Europe.

Summary

CVE-2025-61728 identifies a vulnerability in the Go programming language's standard library, specifically within the archive/zip package. The root cause is an inefficient algorithm used for indexing file names inside ZIP archives, which operates with super-linear time complexity. This algorithm is invoked the first time a file within a ZIP archive is accessed. A malicious actor can craft a ZIP archive designed to exploit this inefficiency, causing the algorithm to consume excessive CPU cycles, leading to a denial of service (DoS) condition. The vulnerability affects all Go versions from the initial release up to and including version 1.25.0. The CVSS v3.1 base score is 6.5 (medium severity), reflecting that the attack vector is network-based (AV:N), requires no privileges (PR:N), but does require user interaction (UI:R) to open the malicious ZIP file. The impact is limited to availability, with no confidentiality or integrity compromise. No patches or fixes have been published yet, and no known exploits are currently active in the wild. This vulnerability is classified under CWE-407 (Inefficient Algorithmic Complexity), which highlights performance degradation risks due to algorithmic inefficiencies. The threat is particularly relevant for applications that automatically process ZIP files, such as web services, CI/CD pipelines, or automated file ingestion systems written in Go. Attackers could exploit this to disrupt services by causing resource exhaustion, potentially leading to downtime or degraded performance.

CWE-407Inefficient Algorithmic Complexity (opens in a new tab)
Class weaknessLikelihood of exploit: Low
An algorithm in a product has an inefficient worst-case computational complexity that may be detrimental to system performance and can be triggered by an attacker, typically using crafted manipulations that ensure that the worst case is being reached.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (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 5 Feb 2026, 08:51 UTC

WeaknessesCWE-407

Technical details

References

Community reviews

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