# CVE-2024-26800: tls: fix use-after-free on failed backlog decryption

CVE-2024-26800 is fixed in linux on 1 platform, first by DEBIAN-CVE-2024-26800, released April 4, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2024-26800
- Priority: High
- CVSS: 7.8 (Important)
- EPSS: 0.0075
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 4, 2024
- Weakness: Use After Free
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-26800

## Description

In the Linux kernel, the following vulnerability has been resolved:  tls: fix use-after-free on failed backlog decryption  When the decrypt request goes to the backlog and crypto_aead_decrypt returns -EBUSY, tls_do_decryption will wait until all async decryptions have completed. If one of them fails, tls_do_decryption will return -EBADMSG and tls_decrypt_sg jumps to the error path, releasing all the pages. But the pages have been passed to the async callback, and have already been released by tls_decrypt_done.  The only true async case is when crypto_aead_decrypt returns  -EINPROGRESS. With -EBUSY, we already waited so we can tell tls_sw_recvmsg that the data is available for immediate copy, but we need to notify tls_decrypt_sg (via the new ->async_done flag) that the memory has already been released.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 6.1.85-1 | [DEBIAN-CVE-2024-26800](https://patchblox.com/security/data/fix/linux/debian-cve-2024-26800.md) | Apr 4, 2024 |
| Linux | linux Debian 13.5 (trixie) | 6.7.9-1 | [DEBIAN-CVE-2024-26800](https://patchblox.com/security/data/fix/linux/debian-cve-2024-26800.md) | Apr 4, 2024 |
| Linux | linux Debian 14 | 6.7.9-1 | [DEBIAN-CVE-2024-26800](https://patchblox.com/security/data/fix/linux/debian-cve-2024-26800.md) | Apr 4, 2024 |

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