CVE-2021-44538: cinny_project cinny
Vulnerability summary
CVE-2021-44538 is a critical (CVSS 9.8) vulnerability in cinny_project cinny. EPSS estimates a 1.98% chance of exploitation in the next 30 days, higher than 80.2% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 7 · Related 4Timeline
- 14-12-2021PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
Description
The olm_session_describe function in Matrix libolm before 3.2.7 is vulnerable to a buffer overflow. The Olm session object represents a cryptographic channel between two parties. Therefore, its state is partially controllable by the remote party of the channel. Attackers can construct a crafted sequence of messages to manipulate the state of the receiver's session in such a way that, for some buffer sizes, a buffer overflow happens on a call to olm_session_describe. Furthermore, safe buffer sizes were undocumented. The overflow content is partially controllable by the attacker and limited to ASCII spaces and digits. The known affected products are Element Web And SchildiChat Web.
CVSS metrics
4 scores · 3 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- OSV · DebianEcosystem advisory · calculated9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
1.98%
Chance of exploitation in the next 30 days
Percentile
80%
Versus all other CVEs
30-day change
+0.06 pp
From 1.92% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian3 products
- olm< 3.2.8~dfsg-1
- thunderbird< 1:91.4.1-1
- debian_linuxEOL9.0 | 10.0 | 11.0
Matrix3 products
- element< 1.9.7
- javascript_sdk≥ 2.4.2, < 15.2.1
- olm≥ 3.1.4, < 3.2.8
Ubuntu3 products
- node-matrix-js-sdkAll versions (No fix recorded)
- olmAll versions (No fix recorded)
- thunderbird< 1:91.5.0+build1-0ubuntu0.18.04.1 | < 1:91.5.0+build1-0ubuntu0.20.04.1 | < 1:91.5.0+build1-0ubuntu1
Cinny_project1 product
- cinny< 1.6.0
Mageia1 product
- olm< 3.2.1-1.1.mga8
Schildi1 product
- schildichat< 1.9.7-sc1
6 vendors · 12 products
References
13 links- matrix.org/blog/2021/12/13/disclosure-buffer-overflow-in-libolm-and-matrix-js-sdkX Refsource MISCWEBPatchVendor Advisory
- lists.debian.org/debian-lts-announce/2022/01/msg00001.htmlMailing ListX Refsource MLISTThird Party Advisory