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🛡️ CVE-2023-26303 — markdown-it-py

🟠 CVSS 8.0 — High ✅ No Known Exploit CWE-173 OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

markdown-it-py Denial of Service vulnerability

Denial of service could be caused to markdown-it-py, before v2.2.0, if an attacker was allowed to force null assertions with specially crafted input.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. Rated impact: confidentiality none, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: Low — the attack works reliably, with no preparation.
  • Attack requirements: None — no deployment-specific condition has to hold.
  • Privileges required: Low — an ordinary user account is enough.
  • User interaction: None — nobody has to be tricked into anything.
  • Confidentiality impact: None.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Weakness class

CVE-2023-26303 is classified as CWE-173: Improper Handling of Alternate Encoding. The product does not properly handle when an input uses an alternate encoding that is valid for the control sphere to which the input is being sent.

Affected software

CVE-2023-26303 is recorded against 1 package.

  • markdown-it-py (fixed in 2.2.0)

Timeline and source

Published on 23 February 2023 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from OSV.

References

nvd.nist.gov (Advisory)
github.com (Web)
github.com (Web)
github.com (Web)
github.com (Package)
github.com (Web)

Other advisories for this package

markdown-it-py has other advisories on record. If you are patching this one, these are worth checking on the same host:

Same weakness in other software

These advisories are the same class of weakness (CWE-173: Improper Handling of Alternate Encoding) in other software:

CVE-2023-26303 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
CWE CWE-173
Public Exploit ✅ No
Source OSV
Published 2023-02-23
Updated 2026-08-20
Modified 2026-06-17

Affected Packages

Software From version Fixed in
markdown-it-py — 2.2.0

Site Security Check

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CVE-2023-26303 is rated CVSS 8.0 High. BotEraser scans your installation against known CVE records and tells you whether this vulnerability applies to the versions you actually run.

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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