CVE-2021-32825Public exploit

Arbitrary file read and write via symlink traversal

Published Aug 16, 2021 · Updated Aug 3, 2024

Path traversal in bblfshd before commit 4265465b9b6fb5663c30ee43806126012066aad4 allows attackers to write arbitrary files via a crafted archive. The runtime untar routine validates each link's lexical path but fails to resolve previously created links, allowing chained symlinks to escape the extraction root. Exploitation requires control of an archive processed by bblfshd; writes use the daemon's permissions, while reading system files also requires access to extracted output.

CVSS severity2.7
Low
EPSS probability0.92%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in bblfshd before commit 4265465b9b6fb5663c30ee43806126012066aad4 allows attackers to write arbitrary files via a crafted archive. The runtime untar routine validates each link's lexical path but fails to resolve previously created links, allowing chained symlinks to escape the extraction root. Exploitation requires control of an archive processed by bblfshd; writes use the daemon's permissions, while reading system files also requires access to extracted output.

The record

CVE
CVE-2021-32825
Published
Aug 16, 2021
Updated
Aug 3, 2024
Vendor
bblfsh
Product
bblfshd
Classifications
CWE-23, CWE-59, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 16, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4265465b9b6fb5663c30ee43806126012066aad4

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

bblfsh · bblfshdversion=< 4265465b9b6fb5663c30ee43806126012066aad4

Published CVSS scores

2.7GitHubCVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:L/I:N/A:N
9.1NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
6.5NVDAV:N/AC:L/Au:S/C:P/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-23Relative Path Traversal
CWE-59Improper Link Resolution Before File Access ('Link Following')
T1204.002Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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