CVE-2006-4339: Openssl: openssl: signature forgery via improper pkcs-1 padding removal leading to certificate validation bypass

Modified

AliasesRHSA-2006:0661DEBIAN-CVE-2006-4339DSA-1173-1+1 more

Published 05-09-2006Last modified 30-10-2026

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Vulnerability summary

CVE-2006-4339 is a critical (CVSS 9.1) vulnerability in openssl. EPSS estimates a 3.95% chance of exploitation in the next 30 days, higher than 90.4% of scored vulnerabilities.

Priority

Prioritisesevere

Severe, CVSS 9.1 (CVE.org); no exploitation reported by the 5 checked sources; EPSS 4% (FIRST, 03-11-2026)

Source freshness unavailable

How is this decided?

CVSS score

9.1/10

010

Critical · v3.1 (NVD)

EPSS score

3.95%

0%100%

Low · -1.14 pp in 30 days

KEVNot listedNot listed by any tracked catalog.

RansomwareNot flaggedNo ransomware use recorded.

Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 7 · Related 4

OPENSUSE-SU-2024:10650-1 OPENSUSE-SU-2024:11126-1 OPENSUSE-SU-2024:11127-1 OPENSUSE-SU-2024:11128-1 RHSA-2008:0264 RHSA-2008:0525+1 more

Timeline

05-09-2006
PublishedVulnerability first disclosed.
30-10-2026
Last modifiedVulnerability information updated.

Description

A flaw was found in OpenSSL. When configured to use an RSA key with exponent 3, OpenSSL improperly removes PKCS-1 padding before generating a hash. This allows remote attackers to forge PKCS #1 v1.5 signatures. Consequently, OpenSSL may incorrectly verify X.509 and other certificates, leading to a bypass of trust and authentication mechanisms.

CVSS metrics

4 scores · 3 sources · 2 versions

v3.19.1v2.04.3

EPSS trend

Probability

3.95%

Chance of exploitation in the next 30 days

Percentile

90%

Versus all other CVEs

30-day change

Decrease -1.14 pp

From 5.09% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs

CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Redhat6 products

openssl< 0:0.9.7a-33.18 | < 0:0.9.7a-43.11
openssl-debuginfo< 0:0.9.7a-33.18 | < 0:0.9.7a-43.11
openssl-devel< 0:0.9.7a-33.18 | < 0:0.9.7a-43.11
openssl-perl< 0:0.9.7a-33.18 | < 0:0.9.7a-43.11
openssl096b< 0:0.9.6b-16.43 | < 0:0.9.6b-22.43

Show all 6

Debian2 products

openssl< 0.9.7e-3sarge2 | < 0.9.8b-3
openssl096< 0.9.6m-1sarge2

Openssl1 product

opensslEOL≤ 0.9.7 | 0.9.1c | 0.9.2b | 0.9.3 | 0.9.3a | 0.9.4 | 0.9.5 | 0.9.5:beta1 | 0.9.5:beta2 | 0.9.5a | 0.9.5a:beta1 | 0.9.5a:beta2 | 0.9.6 | 0.9.6:beta1 | 0.9.6:beta2 | 0.9.6:beta3 | 0.9.6a | 0.9.6a:beta1 | 0.9.6a:beta2 | 0.9.6a:beta3 | 0.9.6b | 0.9.6c | 0.9.6d | 0.9.6e | 0.9.6f | 0.9.6g | 0.9.6h | 0.9.6i | 0.9.6j | 0.9.6k | 0.9.6l | 0.9.6m | 0.9.7a | 0.9.7b | 0.9.7c | 0.9.7d | 0.9.7e | 0.9.7f | 0.9.7g | 0.9.7h | 0.9.7i | 0.9.7j | 0.9.8 | 0.9.8a | 0.9.8b

3 vendors · 9 products

References

216 links

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jvn.jp/en/jp/JVN51615542/index.htmlThird Party AdvisoryX Refsource JVN
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sunsolve.sun.com/search/document.do?assetkey=1-26-102759-1Vendor AdvisoryX Refsource SUNALERT
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www.ubuntu.com/usn/usn-339-1Vendor AdvisoryX Refsource UBUNTUPatch
www.vupen.com/english/advisories/2006/3566VDB EntryX Refsource VUPEN
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sunsolve.sun.com/search/document.do?assetkey=1-26-102744-1Vendor AdvisoryX Refsource SUNALERT
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