VulnerabilityPublished 29 Apr 2025Updated 3 Nov 2026

CVE-2025-4035: Libsoup2.4 · A flaw was found in libsoup

Affects libsoup2.4Source GCVE Database

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Not known to be exploited · CVSS 4.3 Medium.

Data as of 3 Nov 2026, 23:13 UTC

CVSS 3.1 base score

4.3Medium

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

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: None
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: 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: 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 29 Apr 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 3 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.

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.10libsoup2.4`pkg:deb/ubuntu/libsoup2.4?arch=source&distro=stonking`Other threats	Affected =2.74.3-10.1ubuntu5	Fixed in–
Ubuntu 26.10libsoup3`pkg:deb/ubuntu/libsoup3?arch=source&distro=stonking`Other threats	Affected =3.6.6-1 =3.6.6-1ubuntu3 =3.6.6-1ubuntu3.1	Fixed in–
Ubuntu 26.04 LTSlibsoup3`pkg:deb/ubuntu/libsoup3?arch=source&distro=resolute`Other threats	Affected 3.6.5-4 – 3.6.6-1ubuntu0.2 8 affected builds	Fixed in–
Ubuntu Pro 26.04 LTSlibsoup2.4`pkg:deb/ubuntu/libsoup2.4?arch=source&distro=esm-apps/resolute`Other threats	Affected 2.74.3-10.1ubuntu4 – 2.74.3-10.1ubuntu5+esm4 6 affected builds	Fixed in–
Ubuntu 25.10libsoup2.4`pkg:deb/ubuntu/libsoup2.4?arch=source&distro=questing`Other threats	Affected 2.74.3-10 – 2.74.3-10.1ubuntu4.1 7 affected builds	Fixed in–
Ubuntu 25.10libsoup3`pkg:deb/ubuntu/libsoup3?arch=source&distro=questing`Other threats	Affected 3.6.5-1 – 3.6.5-4ubuntu0.2 6 affected builds	Fixed in–

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

Description

A flaw was found in libsoup. When handling cookies, libsoup clients mistakenly allow cookies to be set for public suffix domains if the domain contains at least two components and includes an uppercase character. This bypasses public suffix protections and could allow a malicious website to set cookies for domains it does not own, potentially leading to integrity issues such as session fixation.

References

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