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Fencer Vulns
medium 4.7

CVE-2023-36811 json

Archive spoofing vulnerability in borgbackup

published 2023-08-30 3 y ago modified 2026-06-17 4 mo ago also GHSA-8fjr-hghr-4m99 , PYSEC-2023-164 , EUVD-2023-0050

cvss
4.7
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 1%
public exploits
0
none known

Summary

borgbackup is an opensource, deduplicating archiver with compression and authenticated encryption. A flaw in the cryptographic authentication scheme in borgbackup allowed an attacker to fake archives and potentially indirectly cause backup data loss in the repository. The attack requires an attacker to be able to: 1. insert files (with no additional headers) into backups and 2. gain write access to the repository. This vulnerability does not disclose plaintext to the attacker, nor does it affect the authenticity of existing archives. Creating plausible fake archives may be feasible for empty or small archives, but is unlikely for large archives. The issue has been fixed in borgbackup 1.2.5. Users are advised to upgrade. Additionally to installing the fixed code, users must follow the upgrade procedure as documented in the change log. Data loss after being attacked can be avoided by reviewing the archives (timestamp and contents valid and as expected) after any "borg check --repair" and before "borg prune". There are no known workarounds for this vulnerability.

Patch / fix

  • pypi borgbackup 1.2.5
  • borgbackup borg 1.2.5
  • borgbackup Debian 14, Debian 13 1.2.5-1

debian advisories DEBIAN-CVE-2023-36811

  • borgbackup Alpine 3.24, Alpine 3.23, Alpine 3.22 +4 more 1.2.6-r0

alpine advisories ALPINE-CVE-2023-36811

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-36811 updated cvss 4.7

borgbackup: spoofed archive leads to data loss

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.11% chance of exploitation in the next 30 days, higher than 1% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
GitHub 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N
OSV 3.1 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
pypi borgbackup
<1.2.5
1.2.5

Affected products

  • borgbackup borg

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

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.