CVE-2021-21300
Vulnérabilité élevée dans git (git)
Description
Git is an open-source distributed revision control system. In affected versions of Git a specially crafted repository that contains symbolic links as well as files using a clean/smudge filter such as Git LFS, may cause just-checked out script to be executed while cloning onto a case-insensitive file system such as NTFS, HFS+ or APFS (i.e. the default file systems on Windows and macOS). Note that clean/smudge filters have to be configured for that. Git for Windows configures Git LFS by default, and is therefore vulnerable. The problem has been patched in the versions published on Tuesday, March 9th, 2021. As a workaound, if symbolic link support is disabled in Git (e.g. via `git config --global core.symlinks false`), the described attack won't work. Likewise, if no clean/smudge filters such as Git LFS are configured globally (i.e. _before_ cloning), the attack is foiled. As always, it is best to avoid cloning repositories from untrusted sources. The earliest impacted version is 2.14.2. The fix versions are: 2.30.1, 2.29.3, 2.28.1, 2.27.1, 2.26.3, 2.25.5, 2.24.4, 2.23.4, 2.22.5, 2.21.4, 2.20.5, 2.19.6, 2.18.5, 2.17.62.17.6.
Gravité et risque d'exploitation
CVE-2021-21300 obtient un score CVSS de 8.0/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 88.53 %, ce qui la place devant 99.8 % des CVE référencées.
Que faire ?
- Vérifiez si git (versions >= 2.20.0, < 2.20.5, >= 2.22.0, < 2.22.5, >= 2.26.0, < 2.26.3, >= 2.21.0, < 2.21.4, >= 2.18.0, < 2.18.5, >= 2.30.0, < 2.30.1, >= 2.24.0, < 2.24.4, >= 2.25.0, < 2.25.5, >= 2.19.0, < 2.19.6, >= 2.23.0, < 2.23.4, >= 2.14.2, < 2.17.62.17.6, >= 2.27.0, < 2.27.1, >= 2.28.0, < 2.28.1, >= 2.29.0, < 2.29.3) est présent sur votre parc.
- Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
- À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
- Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.
Références
- https://github.com/git/git/security/advisories/GHSA-8prw-h3cq-mghm
- https://lore.kernel.org/git/xmqqim6019yd.fsf%40gitster.c.googlers.com/
- https://git-scm.com/docs/git-config#Documentation/git-config.txt-coresymlinks
- https://git-scm.com/docs/gitattributes#_filter
- https://github.com/git/git/commit/684dd4c2b414bcf648505e74498a608f28de4592
- http://www.openwall.com/lists/oss-security/2021/03/09/3
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LCLJJLKKMS5WRFO6C475AOUZTWQLIARX/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LMXX2POK5X576BSDWSXGU7EIK6I72ERU/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BBPNGLQSYJHLZZ37BO42YY6S5OTIF4L4/
- https://support.apple.com/kb/HT212320
- http://seclists.org/fulldisclosure/2021/Apr/60
- https://security.gentoo.org/glsa/202104-01
- http://packetstormsecurity.com/files/163978/Git-LFS-Clone-Command-Execution.html
- https://lists.debian.org/debian-lts-announce/2022/10/msg00014.html
