# CVE-2026-87864: IMAP APPEND plus CRLF conversion command injection

CVE-2026-87864 is fixed in 6 products on 1 platform, first by DEBIAN-CVE-2026-87864, released October 16, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-87864
- Priority: High
- CVSS: 8.2 (Important)
- EPSS: 0.0083
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 13, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-87864

## Description

Enabling `CURLOPT_CRLF` causes curl to advertise the raw input byte count in the `IMAP APPEND {N}` literal while transmitting line-ending expanded data. The server reads only $N$ bytes for the payload, causing the remaining overflow bytes to be interpreted and executed as pipelined IMAP commands within the authenticated session.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | curl Debian 14 | 8.22.0-1 | [DEBIAN-CVE-2026-87864](https://patchblox.com/security/data/fix/linux/debian-cve-2026-87864.md) | Oct 16, 2026 |
| Linux | curl Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm15 | [curl 7.58.0-2ubuntu3.24+esm15](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-curl-7.58.0-2ubuntu3.24-esm15.md) | Oct 21, 2026 |
| Linux | curl Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm10 | [curl 7.68.0-1ubuntu2.25+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-focal-curl-7.68.0-1ubuntu2.25-esm10.md) | Oct 21, 2026 |
| Linux | curl Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.30 | [curl 7.81.0-1ubuntu1.30](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-curl-7.81.0-1ubuntu1.30.md) | Oct 21, 2026 |
| Linux | curl Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.16 | [curl 8.5.0-2ubuntu10.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-curl-8.5.0-2ubuntu10.16.md) | Oct 21, 2026 |
| Linux | curl Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.8 | [curl 8.18.0-1ubuntu2.8](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-curl-8.18.0-1ubuntu2.8.md) | Nov 7, 2026 |
| Linux | curl sles 15.6 | 8.22.0-150600.4.58.1 | [SUSE-SU-2026:5069-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5069-1.md) | Nov 7, 2026 |
| Linux | curl sles 15.7 | 8.22.0-150700.7.33.1 | [SUSE-SU-2026:5068-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-5068-1.md) | Nov 7, 2026 |
| Linux | libcurl3-gnutls Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm15 | [libcurl3-gnutls 7.58.0-2ubuntu3.24+esm15](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libcurl3-gnutls-7.58.0-2ubuntu3.24-esm15.md) | Oct 21, 2026 |
| Linux | libcurl3-gnutls Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm10 | [libcurl3-gnutls 7.68.0-1ubuntu2.25+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl3-gnutls-7.68.0-1ubuntu2.25-esm10.md) | Oct 21, 2026 |
| Linux | libcurl3-gnutls Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.30 | [libcurl3-gnutls 7.81.0-1ubuntu1.30](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-gnutls-7.81.0-1ubuntu1.30.md) | Oct 21, 2026 |
| Linux | libcurl3-nss Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm15 | [libcurl3-nss 7.58.0-2ubuntu3.24+esm15](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libcurl3-nss-7.58.0-2ubuntu3.24-esm15.md) | Oct 21, 2026 |
| Linux | libcurl3-nss Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm10 | [libcurl3-nss 7.68.0-1ubuntu2.25+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl3-nss-7.68.0-1ubuntu2.25-esm10.md) | Oct 21, 2026 |
| Linux | libcurl3-nss Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.30 | [libcurl3-nss 7.81.0-1ubuntu1.30](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl3-nss-7.81.0-1ubuntu1.30.md) | Oct 21, 2026 |
| Linux | libcurl3t64-gnutls Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.16 | [libcurl3t64-gnutls 8.5.0-2ubuntu10.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libcurl3t64-gnutls-8.5.0-2ubuntu10.16.md) | Oct 21, 2026 |
| Linux | libcurl3t64-gnutls Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.8 | [libcurl3t64-gnutls 8.18.0-1ubuntu2.8](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl3t64-gnutls-8.18.0-1ubuntu2.8.md) | Nov 7, 2026 |
| Linux | libcurl4 Ubuntu 18.04.6 LTS (bionic) | 7.58.0-2ubuntu3.24+esm15 | [libcurl4 7.58.0-2ubuntu3.24+esm15](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libcurl4-7.58.0-2ubuntu3.24-esm15.md) | Oct 21, 2026 |
| Linux | libcurl4 Ubuntu 20.04 LTS (focal) | 7.68.0-1ubuntu2.25+esm10 | [libcurl4 7.68.0-1ubuntu2.25+esm10](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libcurl4-7.68.0-1ubuntu2.25-esm10.md) | Oct 21, 2026 |
| Linux | libcurl4 Ubuntu 22.04.1 LTS (jammy) | 7.81.0-1ubuntu1.30 | [libcurl4 7.81.0-1ubuntu1.30](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcurl4-7.81.0-1ubuntu1.30.md) | Oct 21, 2026 |
| Linux | libcurl4t64 Ubuntu 24.04.5 LTS (noble) | 8.5.0-2ubuntu10.16 | [libcurl4t64 8.5.0-2ubuntu10.16](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libcurl4t64-8.5.0-2ubuntu10.16.md) | Oct 21, 2026 |
| Linux | libcurl4t64 Ubuntu 26.04.1 LTS (resolute) | 8.18.0-1ubuntu2.8 | [libcurl4t64 8.18.0-1ubuntu2.8](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libcurl4t64-8.18.0-1ubuntu2.8.md) | Nov 7, 2026 |

---

Data as of 2026-11-09T13:31:49Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.