# CVE-2026-31719: crypto: krb5enc - fix async decrypt skipping hash verification

> An attacker can bypass integrity verification in Kerberos encryption by exploiting an async decryption flaw in the Linux kernel crypto subsystem.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 May 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-31719, DEBIAN-CVE-2026-31719, GHSA-774g-v4gm-8h6v, UBUNTU-CVE-2026-31719

## What is CVE-2026-31719?

CVE-2026-31719 is a high-severity vulnerability in Linux kernel, published on 1 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

crypto: krb5enc - fix async decrypt skipping hash verification

krb5enc_dispatch_decrypt() sets req->base.complete as the skcipher
callback, which is the caller's own completion handler. When the
skcipher completes asynchronously, this signals "done" to the caller
without executing krb5enc_dispatch_decrypt_hash(), completely bypassing
the integrity verification (hash check).

Compare with the encrypt path which correctly uses
krb5enc_encrypt_done as an intermediate callback to chain into the
hash computation on async completion.

Fix by adding krb5enc_decrypt_done as an intermediate callback that
chains into krb5enc_dispatch_decrypt_hash() upon async skcipher
completion, matching the encrypt path's callback pattern.

Also fix EBUSY/EINPROGRESS handling throughout: remove
krb5enc_request_complete() which incorrectly swallowed EINPROGRESS
notifications that must be passed up to callers waiting on backlogged
requests, and add missing EBUSY checks in krb5enc_encrypt_ahash_done
for the dispatch_encrypt return value.

Unset MAY_BACKLOG on the async completion path so the user won't
see back-to-back EINPROGRESS notifications.

Weakness: CWE-354 (Improper Validation of Integrity Check Value)

## Which versions are affected by CVE-2026-31719?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-31719?

Apply the vendor's patch.

## Is CVE-2026-31719 being exploited?

There is no known exploitation of CVE-2026-31719 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-31719 and fix it if it is affected.

What it is: CVE-2026-31719 is a high-severity vulnerability in Linux kernel, published on 1 May 2026. 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-2026-31719 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-31719/ (Markdown: https://insights.sbomify.com/CVE-2026-31719/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-31719
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-31719
- OSV: https://osv.dev/vulnerability/CVE-2026-31719

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-31719/
Summaries are generated and may contain mistakes; the official description above is the record.