# CVE-2023-36811: Archive spoofing vulnerability in borgbackup

> Attackers with repository write access can spoof archives, potentially causing data loss during maintenance operations in borgbackup.

- **Severity:** Medium 4.7 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 30 Aug 2023
- **Updated:** 13 Feb 2025
- **Also known as:** CLEANSTART-2024-EI10626, DEBIAN-CVE-2023-36811, GHSA-8fjr-hghr-4m99, PYSEC-2023-164, UBUNTU-CVE-2023-36811, openSUSE-SU-2024:13316-1

## What is CVE-2023-36811?

CVE-2023-36811 is a medium-severity vulnerability in borgbackup borg, published on 30 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2023-36811?

3 open source packages ship an affected version, including borgbackup. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `borgbackup` | PyPI | All versions | 1.2.5 |
| `borgbackup` | PyPI | All versions | 1.2.5 |
| `borgbackup` | PyPI | All versions | 1.2.5 |

Products: Borgbackup Borg.

## How do I fix CVE-2023-36811?

Upgrade borgbackup to 1.2.5 or later.

## Is CVE-2023-36811 being exploited?

There is no known exploitation of CVE-2023-36811 in the wild and no public exploit code.

## Other vulnerabilities in borgbackup borg

- [CVE-2017-15914](https://insights.sbomify.com/CVE-2017-15914/): Borg Improper Access Control vulnerability (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-36811 and fix it if it is affected.

What it is: CVE-2023-36811 is a medium-severity vulnerability in borgbackup borg, published on 30 Aug 2023. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-36811 in the wild and no public exploit code.

Affected packages and fixed versions:
- borgbackup (PyPI): affected all versions; fixed in 1.2.5
- borgbackup (PyPI): affected all versions; fixed in 1.2.5
- borgbackup (PyPI): affected all versions; fixed in 1.2.5

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2023-36811/ (Markdown: https://insights.sbomify.com/CVE-2023-36811/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-36811
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-36811
- OSV: https://osv.dev/vulnerability/CVE-2023-36811

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-36811/
Summaries are generated and may contain mistakes; the official description above is the record.