Integer overflow in table parsing extension leads to heap memory corruption

Vulnerability Description

cmark-gfm is GitHub's extended version of the C reference implementation of CommonMark. Prior to versions 0.29.0.gfm.3 and 0.28.3.gfm.21, an integer overflow in cmark-gfm's table row parsing `table.c:row_from_string` may lead to heap memory corruption when parsing tables who's marker rows contain more than UINT16_MAX columns. The impact of this heap corruption ranges from Information Leak to Arbitrary Code Execution depending on how and where `cmark-gfm` is used. If `cmark-gfm` is used for rendering remote user controlled markdown, this vulnerability may lead to Remote Code Execution (RCE) in applications employing affected versions of the `cmark-gfm` library. This vulnerability has been patched in the following cmark-gfm versions 0.29.0.gfm.3 and 0.28.3.gfm.21. A workaround is available. The vulnerability exists in the table markdown extensions of cmark-gfm. Disabling the table extension will prevent this vulnerability from being triggered.

References

• https://github.com/github/cmark-gfm/security/advisories/GHSA-mc3g-88wq-6f4x
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Z55K6VNVKO2G5SNKRCQ2KDG5SKTX5PVV/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TJBFIJEHJZEEDG6MO4MQHZYKUXELH77O/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/F7V3HAM5H6YFJG2QFEXACZR3XVWFTXTC/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/5CYUU662VO6CCXQKVZVOHXX3RGIF2DLQ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RSKUOJ2VAYGTJXPDE2RRPMNLVVMKCI77/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KH4UQA6VWVZU5EW3HNEAB7D7BTCNJSJ2/
• http://packetstormsecurity.com/files/166599/cmark-gfm-Integer-overflow.html