CVE-2025-27810 [Medium] | Authentication Bypass in Mbed Tls

Mbed TLS before 2.28.10 and 3.x before 3.6.3, in some cases of failed memory allocation or hardware errors, uses uninitialized stack memory to compose the TLS Finished message, potentially leading to authentication bypasses such as replays.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-05-03	0.06%	0.20%	+0.15%
2	2025-10-29	0.03%	0.06%	+0.02%
3	2025-08-21	—	0.03%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-05-03

0.06%

0.20%

+0.15%

2025-10-29

0.03%

0.06%

+0.02%

2025-08-21

—

0.03%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.4	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.2	2.7	[email protected]
4.8	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:L) Attackers could change some data, but it’s limited—not everything goes. Availability (A:N) Service keeps running; no real outage angle.	2.2	2.5	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.4

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.2

2.7

[email protected]

4.8

3.1

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:L): Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N): Service keeps running; no real outage angle.

2.2

2.5

[email protected]

OS Trackers for CVE-2025-27810

vendor	priority	summary	link
`alpine`	—	CVE-2025-27810: 2 source package rows (mbedtls, mbedtls2); 89 state rows across 10 repos (3.18-main, 3.19-main, 3.20-main, 3.21-community, 3.21-main, 3.22-community, 3.22-main, 3.23-community, edge-community, edge-main); fixed 10, open 79.	https://security.alpinelinux.org/vuln/CVE-2025-27810
`debian`	not yet assigned	CVE-2025-27810 not yet assigned priority: Debian including 1 source packages (mbedtls), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 3, open 2.	https://security-tracker.debian.org/tracker/CVE-2025-27810
`ubuntu`	medium	CVE-2025-27810 medium priority: Ubuntu including 1 source packages (mbedtls), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, questing, upstream, xenial): released 5, ignored 2, needed 2.	https://ubuntu.com/security/CVE-2025-27810

Affected software / configurations for CVE-2025-27810

Vendor	Product	Version	Raw CPE
arm	mbed_tls	< 2.28.10	cpe:2.3:a:arm:mbed_tls::::::::
trustedfirmware	mbed_tls	>= 3.0.0, < 3.6.3	cpe:2.3:a:trustedfirmware:mbed_tls::::::::

References for CVE-2025-27810

URL	Tags
https://github.com/Mbed-TLS/mbedtls/releases	Release Notes
https://mbed-tls.readthedocs.io/en/latest/security-advisories/mbedtls-security-advisory-2025-03-2/	Vendor Advisory

URL

CVE-2025-27810

Exploit prediction scoring system (EPSS) score for CVE-2025-27810

Common vulnerability scoring system (CVSS) metrics for CVE-2025-27810

Weakness enumeration for CVE-2025-27810

OS Trackers for CVE-2025-27810

Affected software / configurations for CVE-2025-27810

References for CVE-2025-27810