CVE-2026-27459Patch(pyopenssl / pyopenssl)

MEDIUMCVSS 9.8 · CRITICAL

Exploitation ongoing with high activity in latest observed window (1 mentions)

Immediate actions

Patch pyopenssl pyopenssl systems immediately
Assume compromise if assets are exposed

Recommended action window: Immediate (within 24h)

NVD description

pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_callback` returned a cookie value greater than 256 bytes, pyOpenSSL would overflow an OpenSSL provided buffer. Starting in version 26.0.0, cookie values that are too long are now rejected.

pyopenssl CVEs Back to dashboard

4.0/ 10 priority

Sources & remediation

Patch / fix

https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408

Vendor / third-party advisories

https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4

Other references

Weakness type (CWE)

CWE-120

Priority

MEDIUM

Exploitation

ACTIVE

PoC

NONE

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

pyopenssl

Threat summary

Active exploitation appears in 1 classified signals
Patch or workaround signal is available
7 mentions across 6 observed days
Momentum state: stable

What's happening

Active exploitation reported across 1 signal
Patch or workaround mentioned in 3 signals
Technical details provided in 6 signals
General: 2 classified signals
Disposal: 1 classified signal
Peaked 5d ago at 2 mentions (2026-03-18); latest day: 1
7 total mentions across 6 days

Affected systems

Vendors

pyopenssl

Products

pyopenssl

Deep dive

Activity timeline7 mentions / 6d

Signal classification4 categories

Patch

342.9%

General

228.6%

Disposal

114.3%

Active Exploitation

114.3%

Referenced assets7 URLs

By indicator

Classification over time

Date	Total	Labels

2026-03-18	2	Disposal1General1
2026-03-19	1	General1
2026-03-21	1	Patch1
2026-03-24	1	Active Exploitation1
2026-03-27	1	Patch1
2026-06-04	1	Patch1

Full discourse7 posts

Open Source Security mailing list@oss_security203d
Patch
2 CVEs fixed in pyOpenSSL 26.0.0 https://www.openwall.com/lists/oss-security/2026/03/20/5 CVE-2026-27459: Buffer overflow if a DTLS cookie callback returned a cookie longer than DTLS1_COOKIE_LENGTH bytes CVE-2026-27448: set_tlsext_servername_callback exceptions were silently swallowed and handshake would proceed
Post summary
The post announces that CVE‑2026‑27459 and CVE‑2026‑27448 have been fixed in pyOpenSSL 26.0.0, provides technical details of the flaws, and does not mention exploits or active use.
02072654
4.4K followersView on X
اپیک‌تر از همیشه@IranRevolt2026199d
Active Exploitation
نگه میدارن و به گا میرن. به زیبایی. همین هفته پیش برای لایبرری پایتون openssl یه آسیب‌پذیری جدی پیدا شد که مطمئنم از هر دوتا سرور تحت پایتون یکی اسیرشه https://www.sentinelone.com/vulnerability-database/cve-2026-27459/
Post summary
The post announces a serious CVE-2026-27459 in Python's OpenSSL library and suggests it is currently being exploited, though no PoC, exploit code, patch, or debunking is referenced.
00010142
163 followersView on X
ThreatCluster@threatcluster128d
Patch
SUSE fixed three vulnerabilities in Multi-Linux Manager, including CVE-2026-31958 in Tornado causing denial of service and CVE-2026-27459 in pyOpenSSL triggering buffer overflow, according to SUSE advisories published 3 June 2026. https://threatcluster.io/cluster/critical-vulnerabilities-in-suse-multi-linux-manager-affecti-55490848
Post summary
SUSE has released fixes for CVE-2026-31958 and CVE-2026-27459, addressing a denial‑of‑service in Tornado and a buffer overflow in pyOpenSSL, with advisories issued on June 3, 2026.
0000079
289 followersView on X
ThreatCluster@threatcluster197d
Patch
BREAKING: Critical DTLS cookie callback bug CVE-2026-27459 in pyOpenSSL patched in v26.0.0 with python-cryptography 46.0.5, Fedora 43 and CentOS 8 users urged to update via dnf. https://threatcluster.io/cluster/critical-buffer-overflow-vulnerability-in-pyopenssl-requires-a586876c
Post summary
The post announces the CVE‑2026‑27459 patch for pyOpenSSL, urges updates, and gives specific version information but does not include PoC or exploitation details.
0000040
128 followersView on X
CVEarity@CVEarity205d
General
⚡ New CVE Alert: CVE-2026-27459 📊 Severity: 7.2 🚨 Risk Level: High 🧩 Affects: Multiple / Unspecified Products Reference: https://nvd.nist.gov/vuln/detail/CVE-2026-27459 #CVE-2026-27459 #CVE #High #CyberSecurity #InfoSec https://t.co/Jjt5odijkn
Post summary
The tweet merely announces CVE-2026-27459 with its severity score, offering no further technical details or remediation guidance.
0000037
104 followersView on X
CVE@CVEnew206d
General
CVE-2026-27459 pyOpenSSL is a Python wrapper around the OpenSSL library. Starting in version 22.0.0 and prior to version 26.0.0, if a user provided callback to `set_cookie_generate_… https://www.cve.org/CVERecord?id=CVE-2026-27459
Post summary
The text references CVE-2026-27459 in pyOpenSSL, noting affected versions and a callback issue, but provides no evidence of exploitation, patches, or PoC.
00000117
56.7K followersView on X
CyberDudeBivash® | Global Cybersecurity Company@cyberbivash206d
Disposal
🚨 CYBERDUDEBIVASH SENTINEL APEX ALERT 🚨 Threat: CVE-2026-27459 - pyOpenSSL DTLS cookie callback buffer overflow Intel Report: https://ift.tt/v0x1G5q
Post summary
A new CVE, CVE-2026-27459, involving a buffer overflow in pyOpenSSL's DTLS cookie callback function has been reported.
0000037
335 followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	pyopenssl	pyopenssl	-	-	-

Explore more

Back to dashboard pyopenssl CVEs pyopenssl vulnerabilities

What researchers are saying

CVE-2026-27459

اپیک‌تر از همیشه[verified]@IranRevolt2026Active Exploitation

The post announces a serious CVE-2026-27459 in Python's OpenSSL library and suggests it is currently being exploited, though no PoC, exploit code, patch, or debunking is referenced.

ThreatCluster[verified]@threatclusterPatch

SUSE has released fixes for CVE-2026-31958 and CVE-2026-27459, addressing a denial‑of‑service in Tornado and a buffer overflow in pyOpenSSL, with advisories issued on June 3, 2026.

ThreatCluster[verified]@threatclusterPatch

The post announces the CVE‑2026‑27459 patch for pyOpenSSL, urges updates, and gives specific version information but does not include PoC or exploitation details.

Open Source Security mailing list@oss_securityPatch

The post announces that CVE‑2026‑27459 and CVE‑2026‑27448 have been fixed in pyOpenSSL 26.0.0, provides technical details of the flaws, and does not mention exploits or active use.

CVEarity@CVEarityGeneral

The tweet merely announces CVE-2026-27459 with its severity score, offering no further technical details or remediation guidance.

CVE@CVEnewGeneral

The text references CVE-2026-27459 in pyOpenSSL, noting affected versions and a callback issue, but provides no evidence of exploitation, patches, or PoC.

CyberDudeBivash® | Global Cybersecurity Company@cyberbivashDisposal

A new CVE, CVE-2026-27459, involving a buffer overflow in pyOpenSSL's DTLS cookie callback function has been reported.