CVE-2023-26485
Publication date 31 March 2023
Last updated 24 July 2024
Ubuntu priority
Cvss 3 Severity Score
cmark-gfm is GitHub’s fork of cmark, a CommonMark parsing and rendering library and program in C. A polynomial time complexity issue in cmark-gfm may lead to unbounded resource exhaustion and subsequent denial of service. This CVE covers quadratic complexity issues when parsing text which leads with either large numbers of `_` characters. This issue has been addressed in version 0.29.0.gfm.10. Users are advised to upgrade. Users unable to upgrade should validate that their input comes from trusted sources. ### Impact A polynomial time complexity issue in cmark-gfm may lead to unbounded resource exhaustion and subsequent denial of service. ### Proof of concept ``` $ ~/cmark-gfm$ python3 -c ‘pad = “_” * 100000; print(pad + ”.” + pad, end=”″)’ | time ./build/src/cmark-gfm --to plaintext ``` Increasing the number 10000 in the above commands causes the running time to increase quadratically. ### Patches This vulnerability have been patched in 0.29.0.gfm.10. ### Note on cmark and cmark-gfm XXX: TBD [cmark-gfm](https://github.com/github/cmark-gfm) is a fork of [cmark](https://github.com/commonmark/cmark) that adds the GitHub Flavored Markdown extensions. The two codebases have diverged over time, but share a common core. These bugs affect both `cmark` and `cmark-gfm`. ### Credit We would like to thank @gravypod for reporting this vulnerability. ### References https://en.wikipedia.org/wiki/Time_complexity ### For more information If you have any questions or comments about this advisory: * Open an issue in [github/cmark-gfm](https://github.com/github/cmark-gfm)
Status
Package | Ubuntu Release | Status |
---|---|---|
cmark | 24.10 oracular |
Needs evaluation
|
24.04 LTS noble |
Needs evaluation
|
|
22.04 LTS jammy |
Needs evaluation
|
|
20.04 LTS focal |
Needs evaluation
|
|
18.04 LTS bionic |
Needs evaluation
|
|
16.04 LTS xenial | Ignored end of standard support | |
14.04 LTS trusty | Ignored end of standard support | |
cmark-gfm | 24.10 oracular |
Needs evaluation
|
24.04 LTS noble |
Needs evaluation
|
|
22.04 LTS jammy |
Needs evaluation
|
|
20.04 LTS focal |
Needs evaluation
|
|
18.04 LTS bionic | Not in release | |
16.04 LTS xenial | Ignored end of standard support | |
14.04 LTS trusty | Ignored end of standard support |
Severity score breakdown
Parameter | Value |
---|---|
Base score |
|
Attack vector | Network |
Attack complexity | Low |
Privileges required | None |
User interaction | None |
Scope | Unchanged |
Confidentiality | None |
Integrity impact | None |
Availability impact | High |
Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |