Vulnerability in Facebook Below
CVE-2025-27591
A privilege escalation vulnerability existed in the Below service prior to v0.9.0 due to the creation of a world-writable directory at /var/log/below. This could have allowed local unprivileged users to escalate to root privileges through symlink attacks that manipulate files such as /etc/shadow.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.8 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N.
EPSS exploit prediction
EPSS: 0.004 (27.7th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 27.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Facebook Below
- Meta Platforms, Inc Below — versions 0.0.0
Weakness classification (CWE)
Public proof-of-concept exploits
- BridgerAlderson/CVE-2025-27591-PoC
- 0x00Jeff/CVE-2025-27591
- obamalaolu/CVE-2025-27591
- dollarboysushil/Linux-Privilege-Escalation-CVE-2025-27591
- incommatose/CVE-2025-27591-PoC
- rvzsec/CVE-2025-27591
- rvizx/CVE-2025-27591
- Cythonic1/CVE-2025-27591
- 0xDTC/Below-Logger-Symlink-Attack_CVE-2025-27591
- VisaiCyber/CVE-2025-27591-below-
References
- www.facebook.com/security/advisories/cve-2025-27591 (Patch, Vendor Advisory)
- github.com/facebookincubator/below/commit/da9382e6e3e332fd2c3195e22f34977f83f0f… (Patch)
- af854a3a-2127-422b-91ae-364da2661108 (Exploit, Mailing List)
Frequently asked questions
- What is CVE-2025-27591?
- CVE-2025-27591 is a medium-severity vulnerability in Facebook Below, classified under Incorrect Permission Assignment for Critical Resource. CVSS score: 6.8/10. Published 2025-03-11.
- How severe is CVE-2025-27591?
- Medium severity. CVSS v3 base score is 6.8 out of 10.
- Is CVE-2025-27591 known to be exploited?
- 33 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.