CVE-2019-18837 — An issue was discovered in crun before 0

An issue was discovered in crun before 0.10.5. With a crafted image, it doesn't correctly check whether a target is a symlink, resulting in access to files outside of the container. This occurs in libcrun/linux.c and libcrun/chroot_realpath.c.

01What is this vulnerability?

An issue was discovered in crun before 0.10.5. With a crafted image, it doesn't correctly check whether a target is a symlink, resulting in access to files outside of the container. This occurs in libcrun/linux.c and libcrun/chroot_realpath.c.

02Affected products

Vendor	Product	Versions
crun	crun	before 0.10.5

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2019-11-13T20:01:16.000Z
• Last modified: 2024-08-05T02:02:39.524Z

09References

• github.com — https://github.com/containers/crun/pull/173
• github.com — https://github.com/containers/crun/releases/tag/0.10.5
• lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…
• lists.fedoraproject.org — https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedorapro…