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s2n-tls has undefined behavior at process exit

GHSA-rp9h-rf7g-hwgr

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (s2n-tls 0.3.7), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • crates.io s2n-tls

    Affected
    < 0.3.7
    Fixed in
    0.3.7

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
not scored
EPSS
No dated EPSS signal available.
Source description

As published by the source; long descriptions are shortened.

Impact s2n-tls uses the Linux atexit function to register functions that clean up the global state when the process exits. In multi-threaded environments, the atexit handler may clean up state which is still in use by other threads. When this occurs, the exiting process may experience a segmentation fault or other undefined behavior. Customers of AWS services do not need to take action. Applications using s2n-tls should upgrade to the most recent release of s2n-tls. Impacted versions: < v1.5.9. Patches The patch commit 493b771 is included in s2n-tls v1.5.9 [1] Workarounds The atexit handler may be disabled by calling s2ndisableatexit() prior to initializing s2n-tls. The atexit handler is off by default in the patched versions. For further details, refer to s2n-tls Usage Guide: Initialization and Teardown. If you have any questions or comments about this advisory, we ask that you contact AWS/Amazon Security via our vulnerability reporting page [2] or directly via email to…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-rp9h-rf7g-hwgr

Agent brief

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# Patch Next advisory brief: GHSA-rp9h-rf7g-hwgr

Advisory: s2n-tls has undefined behavior at process exit
IDs: GHSA-rp9h-rf7g-hwgr
Record: https://patchnext.com/advisories/ghsa-rp9h-rf7g-hwgr (revision 1, source checked 26 Oct 2026, 15:38 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Unrated
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: s2n-tls 0.3.7. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io s2n-tls: affected < 0.3.7; fixed in 0.3.7

## Suggested inspection (read-only)
- crates.io s2n-tls: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on s2n-tls.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-rp9h-rf7g-hwgr (GitHub-reviewed advisory GHSA-rp9h-rf7g-hwgr lists affected ranges: crates.io s2n-tls >=0 <0.3.7)

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