VulnerabilityPublished 13 Nov 2026

CVE-2026-126190: Soup Sieve · Polynomial-time denial of service in the descendant combinator

Affects wikSource GCVE Database

Compare

Authoritative record:CVE-2026-126190· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in 4.0 : patch wik soon.

Data as of 13 Nov 2026, 21:05 UTC

CVSS 3.1 base score

7.5High

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

Patch: Available – fixed in 4.0

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
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: 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: 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 12 Nov 2026
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 13 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
Homebrewwik`pkg:brew/wik`Other threats	Affected >=2.0.1	Fixed in–

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

AI-suggested

Upgrade Soup Sieve to version 4.0 or later, where the vulnerability is fixed by caching match results to ensure linear-time selector matching. No code changes are required beyond upgrading. If upgrading is not possible, reduce the number of descendant combinators in selectors used on untrusted input, limit the size and nesting depth of untrusted documents, or run selector operations with time limits in isolated worker processes. Avoid using the NOCACHE flag as it disables the fix and reintroduces the vulnerability.

Description

Soup Sieve versions starting from 2.0.1 are vulnerable to a polynomial-time denial of service (DoS) when processing CSS selectors with descendant combinators on deeply nested HTML or XML documents. The time complexity grows polynomially with the nesting depth and the number of descendant combinators, causing excessive CPU usage. This can be exploited by attackers controlling the input documents to cause significant processing delays. The vulnerability is fixed in version 4.0 by introducing caching to reduce the complexity to linear time.

Impact

Applications using Soup Sieve versions >=2.0.1 that run CSS selectors with descendant combinators on untrusted or attacker-controlled documents can experience denial of service due to excessive CPU consumption. This affects services such as scrapers, HTML sanitizers, filters, or any service processing uploaded or fetched markup. The vulnerability does not affect applications that only process trusted documents. The CVSS score is 7.5 (high), reflecting the potential for denial of service without confidentiality or integrity impact.

References

Community reviews

Loading reviews…

Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Nov 2026, 21:05 UTC

Technical details

References

Community reviews

Related threats