# CVE-2023-27560: phpseclib Infinite Loop vulnerability

> An attacker can cause a denial of service via an infinite loop in the PrimeField component of the phpseclib library.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 3 Mar 2023
- **Updated:** 6 Mar 2025
- **Also known as:** DEBIAN-CVE-2023-27560, GHSA-hm7p-r324-hhf3, UBUNTU-CVE-2023-27560

## What is CVE-2023-27560?

CVE-2023-27560 is a high-severity denial of service vulnerability in n/a, published on 3 Mar 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

Math/PrimeField.php in phpseclib 3.x before 3.0.19 has an infinite loop with composite primefields.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2023-27560?

2 open source packages ship an affected version, including phpseclib/phpseclib. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `phpseclib/phpseclib` | Packagist | From 3.0.0 | 3.0.19 |
| `phpseclib/phpseclib` | Packagist | From 3.0.0 | 3.0.19 |

Products: Phpseclib Phpseclib.

## How do I fix CVE-2023-27560?

Upgrade phpseclib/phpseclib to 3.0.19 or later.

## Is CVE-2023-27560 being exploited?

There is no known exploitation of CVE-2023-27560 in the wild and no public exploit code.

## Other vulnerabilities in n/a

- [CVE-2026-32935](https://insights.sbomify.com/CVE-2026-32935/): phpseclib's AES-CBC unpadding susceptible to padding oracle timing attack (high 8.2)
- [CVE-2023-52892](https://insights.sbomify.com/CVE-2023-52892/): Name confusion in x509 Subject Alternative Name fields (high 7.5)
- [CVE-2023-49316](https://insights.sbomify.com/CVE-2023-49316/): Phpseclib needs guardrails on large binaryfield integers (high 7.5)
- [CVE-2026-55599](https://insights.sbomify.com/CVE-2026-55599/): phpseclib: X.509 certificate validation sends attacker-controlled outbound requests (server-side request forgery) via Authority Information Access (medium 5.8)
- [CVE-2026-40194](https://insights.sbomify.com/CVE-2026-40194/): phpseclib has a variable-time HMAC comparison in SSH2::get_binary_packet() using != instead of hash_equals() (low 3.7)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-27560 and fix it if it is affected.

What it is: CVE-2023-27560 is a high-severity denial of service vulnerability in n/a, published on 3 Mar 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2023-27560 in the wild and no public exploit code.

Affected packages and fixed versions:
- phpseclib/phpseclib (Packagist): affected from 3.0.0; fixed in 3.0.19
- phpseclib/phpseclib (Packagist): affected from 3.0.0; fixed in 3.0.19

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-2023-27560/ (Markdown: https://insights.sbomify.com/CVE-2023-27560/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-27560
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-27560
- OSV: https://osv.dev/vulnerability/CVE-2023-27560

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-27560/
Summaries are generated and may contain mistakes; the official description above is the record.