Symlink guard bypass in unarchive module allows planting symlinks during extraction

published 2026-07-08 4 mo ago modified 2026-10-25 14 d ago also GHSA-xpf3-p7gm-7756 , PYSEC-2026-3719 , EUVD-2026-42295

cvss: 3.1; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits: 0; none known

BBOT's unarchive module rejects archives containing symlink entries before extraction, but for zip and 7z archives it failed to detect symlinks whose listing carries a DOS-attribute prefix before the unix mode, as produced by legacy versions of p7zip. Such an archive, downloaded and extracted during a scan (for example via filedownload), bypassed the guard and caused an attacker-controlled symlink to be written into the extraction directory. The effect is limited to planting the symlink (its target is not written through), and only hosts using such a legacy p7zip build are affected; current mainline 7-Zip is not.

Patch / fix

fixed in 1 links 2

pypi bbot 3.0.0

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 4 mo ago (2026-07-08)

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
OSV	3.1	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N
GitHub	3.1	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
pypi	bbot	>=2.3.1, <3.0.0	3.0.0

Affected products

Black Lantern Security BBOT

Classification

Weakness

CWE-59 Improper Link Resolution Before File Access
CWE-22 Improper Limitation of a Pathname to a Restricted Directory

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary