CVE catalog

CVE-2026-59638

Severity: Critical · CVSS 9.3CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Amber
Published: Aug 2, 2026, 10:00:00 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.34% · Oct 25, 2026

In Bouncy Castle for Java before 1.85, JSSE hostname verifier CN-fallback enabled by default despite documented opt-in. This issue also affects Bouncy Castle for Java LTS before 2.73.12, and Bouncy Castle for Java FIPS (BC-FJA) before bctls-fips 1.0.24 (1.0.X series), 2.0.24 (2.0.X series) and 2.1.24 (2.1.X series).

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	bouncycastle	sid	`1.86.2-1`	fixed
Debian	bouncycastle	forky	`1.86-1`	fixed
Debian	bouncycastle	trixie	`1.80-3`	vulnerable
Debian	bouncycastle	bookworm	`1.72-2`	vulnerable
Cpe	bc-java	Not reported	`1.85`	fixed
Cpe	bctls-fips	Not reported	`2.1.24`	fixed
Cpe	bouncy_castle_for_java_lts	Not reported	Not reported	unknown

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	bouncycastle	source	sid	`1.86-1`	not yet assigned	Not reported	[1143536]
Debian	bouncycastle	source	forky	`1.86-1`	not yet assigned	Not reported	[1143536]
Debian	bouncycastle	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1143536]
Debian	bouncycastle	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1143536]
Cpe	bc-java	cpe	Not reported	`1.85`	Not reported	NVD-CVE-2026-59638	Not reported
Cpe	bctls-fips	cpe	Not reported	`2.1.24`	Not reported	NVD-CVE-2026-59638	Not reported

[Debian bug #1143536]

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libbcjmail-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
[libbcmail-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
[libbcpg-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
[libbcpkix-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
[libbcprov-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
[libbctls-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
[libbcutil-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12
- 1.72-2 · all · bookworm
  Affected
  nvd · bouncycastle · debian · bookworm; nvd · bouncycastle · debian · 12

[Debian 13 (Trixie)]

[libbcjmail-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
[libbcmail-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
[libbcpg-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
[libbcpkix-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
[libbcprov-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
[libbctls-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
[libbcutil-java]Affected
Source package: [bouncycastle]
Details (2)
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13
- 1.80-3 · all · trixie
  Affected
  nvd · bouncycastle · debian · 13

Observed: Oct 23, 2026, 9:42:40 PM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]