GHSA-w9m9-85wc-3x92 CVE-2026-9358
postcss-selector-parser allows denial of service through uncontrolled AST recursion
- Severity
- 2.1 / 10
- Low · CVSS 4.0
- Exploit chance (EPSS)
- 0.33%
- Chance of exploitation in the next 30 days. Higher than 25.61% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-404 Improper Resource Shutdown or Release
- Fix
6.1.3- Upgrade postcss-selector-parser to this version or later
Description
A vulnerability was determined in postcss-selector-parser before 6.1.3 and 7.1.1. Affected is the function toString of the file src/selectors/container.js of the component AST Serialization. Executing a manipulation can lead to uncontrolled recursion. It is possible to launch the attack remotely. The exploit has been publicly disclosed and may be utilized. The vendor explains, that according to his definition "DoS on server-side on user-generated CSS is low risk for us (since most users compile own CSS with PostCSS)."
Affected versions
npm
| Package | Vulnerable | Fixed in |
|---|---|---|
| postcss-selector-parser | >= 6.1.0, < 6.1.3 |
6.1.3 |
| postcss-selector-parser | >= 7.1.0, < 7.1.3 |
7.1.3 |
| postcss-selector-parser | >= 6.1.0, < 6.1.3 |
6.1.3 |
| postcss-selector-parser | >= 7.1.0, < 7.1.3 |
7.1.3 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
postcss-selector-parser npm → 6.1.3
- npm
npm install postcss-selector-parser@6.1.3- yarn
yarn add postcss-selector-parser@6.1.3- pnpm
pnpm add postcss-selector-parser@6.1.3
Severity breakdown
CVSS 4.0 2.1
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- Passive
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- Low
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
- Exploit maturity
- Proof of concept
CVSS 3.1 4.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Weakness
CWE-404: Improper Resource Shutdown or Release
The product does not release or incorrectly releases a resource before it is made available for re-use.
How to prevent it
- Requirements: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, languages such as Java, Ruby, and Lisp perform automatic garbage collection that releases memory for objects that have been deallocated.
- Implementation: It is good practice to be responsible for freeing all resources you allocate and to be consistent with how and where you free memory in a function. If you allocate memory that you intend to free upon completion of the function, you must be sure to free the memory at all exit points for that function including error conditions.
- Implementation: Memory should be allocated/freed using matching functions such as malloc/free, new/delete, and new[]/delete[].
- Implementation: When releasing a complex object or structure, ensure that you properly dispose of all of its member components, not just the object itself.
References
Advisories
Fixes and patches
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-rj75-hqrm-r3gf PostCSS: Quadratic complexity in flat selector parsing allows CPU exhaustion | Medium | Also affects postcss-selector-parser |
| PYSEC-2026-4319 A security flaw has been discovered in vllm-project vLLM up to 0.31.0. | Medium | Same weakness, CWE-404 |
| PYSEC-2026-4186 A flaw has been found in vllm-project vLLM up to 0.26.0. | Medium | Same weakness, CWE-404 |
| GHSA-9x8q-7h8h-wcw9 aiohttp: Payload Response Resources Are Not Closed After Mid-Body Disconnect | High | Same weakness, CWE-404 |
| GHSA-98f3-hwg4-4rf7 vllm has Improper Resource Shutdown or Release | Medium | Same weakness, CWE-404 |
| GHSA-3298-56p6-rpw2 OpenClaw has incomplete Fix for CVE-2026-27486: Unvalidated SIGKILL in `!stop` Chat Command via `shell-utils.ts` | Medium | Same weakness, CWE-404 |
| GHSA-h656-5vcf-cm23 OpenClaw: Unauthorized Telegram Senders Trigger Media Download and Disk Write Before Access Check | Medium | Same weakness, CWE-404 |
| GHSA-rxpr-wq63-jr7p Open Babel has a NULL pointer dereference in CDXML OBAtom::GetExplicitValence | Medium | Same weakness, CWE-404 |
Credits: MoOx
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