---
title: "CVE-2026-72897: OpenSSL - Out-of-Bounds Read & Write"
description: "OpenSSL TLS server contains an out-of-bounds read and write caused by calling SSL_set_SSL_CTX() to switch SSL_CTX during handshake without refreshing internal array size, letting remote peers cause heap corruption and denial of service, exploit requires use of different SSL_CTX with more provider signature algorithms."
url: https://panop.io/threat-heartbeat/CVE-2026-72897/
---

# CVE-2026-72897 OpenSSL - Out-of-Bounds Read & Write

OpenSSL TLS server contains an out-of-bounds read and write caused by calling SSL\_set\_SSL\_CTX() to switch SSL\_CTX during handshake without refreshing internal array size, letting remote peers cause heap corruption and denial of service, exploit requires use of different SSL\_CTX with more provider signature algorithms.

CVSS base score 7.5 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Not required

EPSS

0.27% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-72897)

## Details

Type

Out-of-Bounds Read

Impact

Denial Of Service

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Published

29 September 2026

Updated

15 October 2026

Weakness

[CWE-787](https://cwe.mitre.org/data/definitions/787.html)

## Vendor fix

Update to the latest OpenSSL version where this issue is fixed.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-72897](https://nvd.nist.gov/vuln/detail/CVE-2026-72897)
- [https://github.com/openssl/openssl/commit/00646e5085a0d12d29e0d2f9b9bc5f7111a50922](https://github.com/openssl/openssl/commit/00646e5085a0d12d29e0d2f9b9bc5f7111a50922)
- [https://github.com/openssl/openssl/commit/4135f553c9d3ba4a09fe752f5d30af2a6a092b2e](https://github.com/openssl/openssl/commit/4135f553c9d3ba4a09fe752f5d30af2a6a092b2e)
- [https://github.com/openssl/openssl/commit/9c54d209486f6b1ad79fe2179c40f13200fa4f61](https://github.com/openssl/openssl/commit/9c54d209486f6b1ad79fe2179c40f13200fa4f61)
- [https://github.com/openssl/openssl/commit/e87ed26b298a74d8ba61a53e9c7bcd1acac6b814](https://github.com/openssl/openssl/commit/e87ed26b298a74d8ba61a53e9c7bcd1acac6b814)
- [https://openssl-library.org/news/secadv/20260929.txt](https://openssl-library.org/news/secadv/20260929.txt)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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