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CVE-2026-9358

postcss-selector-parser AST Serialization container.js toString recursion

5.3 MediumFix available

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
Low

Exploit likelihood

0.33%Up 0.3 points since May 24, 2026
90%50%10%1%

What each source reports

CVE List Score used 5.3

postcss-selector-parser AST Serialization container.js toString recursion

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Record
CVE-2026-9358
CVSS 4.0
5.3 MediumCVSS: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
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
CVSS 3.0
4.3 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:P/RL:O/RC:C
CVSS 2.0
5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P/E:POC/RL:OF/RC:C
Weakness
CWE-674, CWE-404
Updated
2026-11-02
EUVDEUVD-2026-31571 5.3

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Record
EUVD-2026-31571
CVSS 4.0
5.3 MediumCVSS: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
Updated
2026-11-02
GitHub AdvisoriesGHSA-w9m9-85wc-3x92 2.1

postcss-selector-parser allows denial of service through uncontrolled AST recursion

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)."

Record
GHSA-w9m9-85wc-3x92
CVSS 4.0
2.1 LowCVSS: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
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Weakness
CWE-404
Updated
2026-11-02
NVD 2.1

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Record
CVE-2026-9358
CVSS 4.0
2.1 LowCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:N/A:P
Weakness
CWE-404, CWE-674
Updated
2026-11-02
OSV 2.1

postcss-selector-parser AST Serialization container.js toString recursion

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Record
CVE-2026-9358
CVSS 4.0
2.1 LowCVSS: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
Weakness
CWE-404, CWE-674
Updated
2026-11-02
OSVDEBIAN-CVE-2026-9358 2.1

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Record
DEBIAN-CVE-2026-9358
CVSS 4.0
2.1 LowCVSS: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/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-02
Show 6 moreShow less
OSVGHSA-w9m9-85wc-3x92 2.1

postcss-selector-parser allows denial of service through uncontrolled AST recursion

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)."

Record
GHSA-w9m9-85wc-3x92
CVSS 4.0
2.1 LowCVSS: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
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Weakness
CWE-404
Updated
2026-11-02
OSVRHSA-2026:22934 7.5

Red Hat Security Advisory: Red Hat Hardened Images RPMs bug fix and enhancement update

Record
RHSA-2026:22934
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2026-9358 2.1

A vulnerability was determined in postcss-selector-parser up to 6.1.2/7.1.2. 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. Upgrading to version 6.1.3 and 7.1.3 is able to address this issue. This patch is called 5bc698cef66f8abd12610dc623e5d67cbc0f869d. It is suggested to upgrade the affected component. 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)." The commits were backported to 6.x branch, which was the most downloaded version.

Record
UBUNTU-CVE-2026-9358
CVSS 4.0
2.1 LowCVSS: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
CVSS 3.1
4.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L
Updated
2026-11-02
OSVCLSA-2026-1792450509 No score

TuxCare security update for postcss-selector-parser (2 CVEs)

TuxCare rebuilt postcss-selector-parser to address 2 CVEs. Fixed in 7.1.0-tuxcare.1.

Record
CLSA-2026-1792450509
Updated
2026-11-02
OSVCLSA-2026-1792476079 No score

TuxCare security update for postcss-selector-parser (2 CVEs)

TuxCare rebuilt postcss-selector-parser to address 2 CVEs. Fixed in 6.1.2-tuxcare.1.

Record
CLSA-2026-1792476079
Updated
2026-11-02
OSVCLSA-2026-1792489937 No score

TuxCare security update for postcss-selector-parser (2 CVEs)

TuxCare rebuilt postcss-selector-parser to address 2 CVEs. Fixed in 7.1.1-tuxcare.1.

Record
CLSA-2026-1792489937
Updated
2026-11-02

Affected packages

Affected packages
PackageAffectedFixed
postcss-selector-parser
npm
6.1.0 up to 6.1.3
6.1.3
postcss-selector-parser
npm
7.1.0 up to 7.1.3
7.1.3
postcss-selector-parser
TuxCare:npm
From an advisory covering 2 CVEs
7.1.0-tuxcare.0 up to 7.1.0-tuxcare.1, plus listed versions
7.1.0
7.1.0-tuxcare.1
postcss-selector-parser
TuxCare:npm
From an advisory covering 2 CVEs
6.1.2-tuxcare.0 up to 6.1.2-tuxcare.1, plus listed versions
6.1.2
6.1.2-tuxcare.1
postcss-selector-parser
TuxCare:npm
From an advisory covering 2 CVEs
7.1.1-tuxcare.0 up to 7.1.1-tuxcare.1, plus listed versions
7.1.1
7.1.1-tuxcare.1
node-css-loader
Debian:12
All versions, plus listed versions
6.11.0+~cs15.5.7-16.11.0+~cs15.5.7-26.11.0+~cs15.5.7-36.7.2+~cs14.0.11-16.8.1+~cs14.0.17-16.8.1+~cs14.0.17-26.8.1+~cs14.1.4-1
None known
node-css-loader
Debian:13
All versions, plus listed versions
6.11.0+~cs15.5.7-16.11.0+~cs15.5.7-26.11.0+~cs15.5.7-36.8.1+~cs14.0.17-16.8.1+~cs14.0.17-26.8.1+~cs14.1.4-1
None known
node-css-loader
Debian:14
before 6.8.1+~cs14.1.4-1, plus listed versions
6.8.1+~cs14.0.17-16.8.1+~cs14.0.17-2
6.8.1+~cs14.1.4-1
cargo
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
clippy
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
Show 23 moreShow less
Affected packages
PackageAffectedFixed
rust
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-analyzer
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-debugger-common
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-doc
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-gdb
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-lldb
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-src
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-aarch64-unknown-none-softfloat
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-aarch64-unknown-uefi
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-i686-pc-windows-gnu
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-wasm32-unknown-unknown
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-wasm32-wasip1
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-x86_64-pc-windows-gnu
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-x86_64-unknown-none
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rust-std-static-x86_64-unknown-uefi
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
rustfmt
Red Hat:hummingbird:1
From an advisory covering 6 CVEs
before 0:1.96.0-1.hum1
0:1.96.0-1.hum1
node-css-loader
Ubuntu:20.04:LTS
All versions, plus listed versions
1.0.1-11.0.1+repack-1
None known
node-css-loader
Ubuntu:22.04:LTS
All versions, plus listed versions
5.0.1+~cs14.0.5-1
None known
node-css-loader
Ubuntu:24.04:LTS
All versions, plus listed versions
6.7.2+~cs14.0.11-16.8.1+~cs14.0.17-1
None known
node-css-loader
Ubuntu:25.10
All versions, plus listed versions
6.8.1+~cs14.0.17-1
None known
node-css-loader
Ubuntu:26.10
All versions, plus listed versions
6.8.1+~cs14.0.17-26.8.1+~cs14.1.4-16.11.0+~cs15.5.7-16.11.0+~cs15.5.7-2
None known
node-css-loader
Ubuntu:26.04:LTS
All versions, plus listed versions
6.8.1+~cs14.0.17-16.8.1+~cs14.0.17-2
None known

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-9358 is a medium vulnerability (CVSS 5.3) in postcss-selector-parser, published May 24, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.33%, the 25th percentile. Fixed in postcss-selector-parser 6.1.3.

References

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