VulnerabilityPublished 26 Nov 2025

CVE-2025-63938: tinyproxy · CVE-2025-63938 is an integer overflow

Affects tinyproxySource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium : upgrade to 1.11.3 when convenient.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 17% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.11.3

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
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: 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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 26 Nov 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

Upgrade tinyproxy/tinyproxy to 1.11.3.

Affected software

Product	Affected	Fixed in
GitHubtinyproxy/tinyproxy`pkg:github/tinyproxy/tinyproxy`Other threats	Affected <1.11.3	Fixed in 1.11.3

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

AI-suggested

Organizations should immediately inventory their use of Tinyproxy and identify any instances running version 1.11.2 or earlier. In the interim, restrict network access to Tinyproxy instances, limiting exposure to trusted networks only. Employ network segmentation and firewall rules to prevent unauthorized external access to proxy services. Implement strict logging and monitoring of proxy traffic to detect anomalous behavior indicative of exploitation attempts. Consider deploying Web Application Firewalls (WAFs) or Intrusion Detection Systems (IDS) with signatures tuned for proxy anomalies. Where feasible, replace Tinyproxy with alternative proxy solutions that have active security support. Conduct regular security assessments and penetration tests focusing on proxy infrastructure.

Description

CVE-2025-63938 is an integer overflow vulnerability in Tinyproxy versions up to 1.11.2, specifically in the strip_return_port() function within src/reqs.c. This flaw allows an unauthenticated remote attacker to cause a partial compromise of confidentiality and integrity without requiring user interaction. The vulnerability has a CVSS score of 6.5 (medium severity) and does not impact availability. No known exploits are currently in the wild. The vulnerability arises from improper handling of integer values leading to overflow, which could be leveraged to manipulate proxy request processing. European organizations using Tinyproxy as a lightweight HTTP proxy may face risks, especially those in sectors relying on secure proxying for internal or external communications.

Impact

For European organizations, the integer overflow in Tinyproxy could lead to unauthorized disclosure of sensitive information passing through the proxy or unauthorized modification of HTTP requests and responses, undermining data confidentiality and integrity. Sectors such as finance, government, and telecommunications that rely on proxy servers for secure and controlled internet access are particularly at risk. While availability is not directly impacted, the breach of confidentiality or integrity could facilitate further attacks, including data exfiltration or man-in-the-middle scenarios. Organizations using Tinyproxy in perimeter defenses or internal network segments may inadvertently expose critical data flows. The absence of known exploits currently reduces immediate risk, but the medium severity rating and ease of exploitation without authentication necessitate proactive measures. Failure to address this vulnerability could lead to compliance issues under GDPR if personal data is compromised. Additionally, the vulnerability could be leveraged as a foothold for lateral movement within networks, amplifying its impact.

CWE-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.3 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Dec 2025, 16:54 UTC

WeaknessesCWE-190

Technical details

References

Community reviews

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