VulnerabilityPublished 13 Aug 2026Updated 1 Nov 2026

CVE-2026-49477: Soup Sieve · Regular Expression Denial of Service (ReDoS) via Selector Parser

Affects manimSource GCVE Database

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Not known to be exploited · CVSS 7.5 High : upgrade to 0.20.1_1 soon.

Data as of 1 Nov 2026, 22:58 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 0.6% chance of exploitation in 30 days – higher than 50% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.20.1_1

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 13 Aug 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 1 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

Upgrade manim to 0.20.1_1.

Affected software

Product	Affected	Fixed in
Homebrewmanim`pkg:brew/manim`Other threats	Affected >=0.19.0 <0.20.1_1	Fixed in 0.20.1_1

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

AI-suggested

A fix for this vulnerability is available in soupsieve version 0.20.1_1. Users should upgrade to this version or later to remediate the issue. Until patched, avoid passing untrusted or user-supplied CSS selectors to soupsieve.compile() or Beautiful Soup's select methods. Implementing input validation or limiting selector input size may reduce risk but is not a complete mitigation. Patch status is confirmed by the vendor's fixed version information.

Description

A Regular Expression Denial of Service (ReDoS) vulnerability exists in soupsieve's CSS selector parser due to a regex pattern that suffers from catastrophic backtracking when processing attribute selectors with unterminated quoted values. This flaw allows an attacker to cause CPU exhaustion by supplying a crafted CSS selector string, leading to thread blocking and significant processing delays. The vulnerability affects soupsieve versions from 0.19.0 up to but not including 0.20.1_1 and has been assigned CVE-2026-49477. A fix is available in version 0.20.1_1.

Impact

An attacker can cause a denial of service by exhausting CPU resources on servers running Python applications that use soupsieve to compile user-supplied CSS selectors. The attack requires only a small payload (around 300 bytes) and can be tuned to increase processing delays exponentially. This leads to thread blocking and potential service disruption without increased memory usage. No authentication is required to exploit this vulnerability, making it a high-severity risk for affected applications.

Summary

The soupsieve CSS selector engine uses a regex pattern in css_parser.py to tokenize attribute selector values, matching quoted and unquoted strings. When an attribute selector contains an unterminated quoted value (e.g., an opening quote without a closing quote), the regex engine experiences catastrophic backtracking due to overlapping character classes and alternation branches. This causes exponential growth in backtracking steps proportional to input length, resulting in CPU exhaustion and thread blocking. A payload of approximately 300 bytes can cause the regex engine to hang for over 3 seconds, with each additional byte roughly doubling the processing time. The vulnerability affects any application that compiles untrusted CSS selectors using soupsieve.compile() or Beautiful Soup's select methods. The issue has been independently validated and a patch is available in soupsieve version 0.20.1_1.

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Affected software

Description

AI analysisMachine-generated, updated 1 Nov 2026, 20:01 UTC

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