Bug 2496798

Summary:	CVE-2026-55952 erlang: Erlang/OTP: Denial of Service in TLS 1.3 session ticket handling [fedora-all]
Product:	[Fedora] Fedora	Reporter:	jkelly <jkelly>
Component:	erlang	Assignee:	Peter Lemenkov <lemenkov>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	high
Version:	rawhide	CC:	jonathan, lemenkov, rhbugs, rjones
Target Milestone:	---	Keywords:	Security, SecurityTracking
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:	{"flaws": ["e00cbf7d-cacc-4494-a9a2-aac94896718a"]}
Fixed In Version:	erlang-26.2.5.21-4.fc43 erlang-26.2.5.21-4.fc44	Doc Type:	---
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2026-07-19 03:56:04 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	2496626

Description jkelly 2026-07-03 09:39:18 UTC

Disclaimer: Community trackers are created by Red Hat Product Security team on a best effort basis. Package maintainers are required to ascertain if the flaw indeed affects their package, before starting the update process.

The Erlang/OTP ssl application does not validate that the PSK identity list and binder list carried in a TLS 1.3 ClientHello pre-shared key extension have equal length before passing them to the session ticket handler. In tls_handshake_1_3:handle_pre_shared_key/3, an OfferedPreSharedKeys record with a mismatched number of identities and binders is forwarded directly to tls_server_session_ticket:use/4, which crashes the session ticket handler process.

An unauthenticated remote attacker can send a single crafted ClientHello to a TLS 1.3 server with session tickets enabled (stateful or stateless mode) and permanently disrupt session ticket handling on that listener. New TLS 1.3 handshakes complete but subsequently crash when the server attempts to issue a session ticket, effectively making TLS 1.3 unusable on the affected listener until the ssl application is restarted. TLS 1.2 connections are not affected.

This issue affects OTP from 22.2 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 9.5 before 11.7.3, 11.6.0.3 and 11.2.12.10.

Comment 1 Peter Lemenkov 2026-07-10 16:26:54 UTC

Fixed in Fedora rawhide (f45) via erlang-27.3.4.14-1.fc45, which ships the upstream OTP fix (ssl-11.2.12.10, in OTP 27.3.4.14).

f43 and f44 remain on the OTP 26.x line, which did not receive an upstream fix for this issue, so a downstream backport is required. Backports for f43/f44 are prepared; updates will follow via Bodhi.

Comment 2 Fedora Update System 2026-07-10 17:12:27 UTC

FEDORA-2026-dcf80dc1ff (erlang-26.2.5.21-4.fc44) has been submitted as an update to Fedora 44.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-dcf80dc1ff

Comment 3 Fedora Update System 2026-07-10 17:12:42 UTC

FEDORA-2026-965be97ac0 (erlang-26.2.5.21-4.fc43) has been submitted as an update to Fedora 43.
https://bodhi.fedoraproject.org/updates/FEDORA-2026-965be97ac0

Comment 4 Fedora Update System 2026-07-11 01:34:48 UTC

FEDORA-2026-dcf80dc1ff has been pushed to the Fedora 44 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-dcf80dc1ff`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-dcf80dc1ff

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 5 Fedora Update System 2026-07-11 01:47:56 UTC

FEDORA-2026-965be97ac0 has been pushed to the Fedora 43 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --refresh --advisory=FEDORA-2026-965be97ac0`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2026-965be97ac0

See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.

Comment 6 Fedora Update System 2026-07-19 03:56:04 UTC

FEDORA-2026-965be97ac0 (erlang-26.2.5.21-4.fc43) has been pushed to the Fedora 43 stable repository.
If problem still persists, please make note of it in this bug report.

Comment 7 Fedora Update System 2026-07-19 05:47:33 UTC

FEDORA-2026-dcf80dc1ff (erlang-26.2.5.21-4.fc44) has been pushed to the Fedora 44 stable repository.
If problem still persists, please make note of it in this bug report.