CVE-2025-47917
published 2025-07-20CVE-2025-47917: Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function…
PriorityP260critical9.8CVSS 3.1
AVNACLPRNUINSUCHIHAH
EXPLOIT
EPSS
2.44%
84.2th percentile
Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function mbedtls_x509_string_to_names() takes a head argument that is documented as an output argument. The documentation does not suggest that the function will free that pointer; however, the function does call mbedtls_asn1_free_named_data_list() on that argument, which performs a deep free(). As a result, application code that uses this function (relying only on documented behavior) is likely to still hold pointers to the memory blocks that were freed, resulting in a high risk of use-after-free or double-free. In particular, the two sample programs x509/cert_write and x509/cert_req are affected (use-after-free if the san string contains more than one DN).
Affected
10 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| arm | mbed_tls | < 3.6.4 | 3.6.4 |
| debian | mbedtls | < mbedtls 2.16.9-0.1+deb11u3 (bullseye) | mbedtls 2.16.9-0.1+deb11u3 (bullseye) |
| mbed | mbedtls | < 3.6.4 | 3.6.4 |
| mbed | mbedtls | >= 0 < 2.16.9-0.1+deb11u3 | 2.16.9-0.1+deb11u3 |
| mbed | mbedtls | >= 0 < 3.6.4-1 | 3.6.4-1 |
| mbed | mbedtls | >= 0 < 3.6.4-1 | 3.6.4-1 |
| mbed | mbedtls | >= 0 < 2.8.0-1ubuntu0.1~esm1 | 2.8.0-1ubuntu0.1~esm1 |
| mbed | mbedtls | >= 0 < 2.16.4-1ubuntu2+esm1 | 2.16.4-1ubuntu2+esm1 |
| mbed | mbedtls | >= 0 < 2.28.0-1ubuntu0.1~esm1 | 2.28.0-1ubuntu0.1~esm1 |
| mbed | mbedtls | >= 0 < 2.28.8-1ubuntu0.1~esm1 | 2.28.8-1ubuntu0.1~esm1 |
Detection & IOCsextracted from sources · hover to see the quote
bytes↗
48 31 d2 b8 29 00 00 00 be 01 00 00 00 bf 02 00 00 00 0f 05 48 89 c7 49 89 c4 48 83 ec 10 c7 44 24 0c bd 5c a8 c0 66 c7 44 24 0a 11 c1 66 c7 44 24 08 02 00 48 89 e6 ba 10 00 00 00 b8 2a 00 00 00 0f 05 4c 89 e7 be 02 00 00 00 b8 21 00 00 00 0f 05 48 ff ce 79 f4 48 31 d2 48 b8 62 2f 73 62 61 73 68 00 50 48 b8 2f 75 73 72 2f 62 69 6e 50 48 89 e7 52 57 48 89 e6 b8 3b 00 00 00 0f 05
- →Trigger condition: use-after-free is triggered when mbedtls_x509_string_to_names() is called a second time with a san string containing more than one DN (e.g., 'CN=AAAA,CN=BBBB'), causing the function to free the head pointer that the caller still holds. ↗
- →The exploit requires ASLR to be disabled (/proc/sys/kernel/randomize_va_space == 0) for reliable exploitation; detect attempts to disable ASLR as a precursor indicator. ↗
- →The exploit shellcode connects back to a remote IP on port 4454 using a reverse shell to /usr/bin/sbash; monitor for unexpected outbound connections on port 4454 from processes linked to mbedtls. ↗
- →The exploit uses mmap with PROT_READ|PROT_WRITE|PROT_EXEC and MAP_ANON|MAP_PRIVATE to allocate executable shellcode pages; detect anonymous RWX memory mappings in processes using mbedtls. ↗
- →Vulnerable code path: mbedtls_x509_string_to_names() internally calls mbedtls_asn1_free_named_data_list() on the head argument without documenting this behavior, performing a deep free. Monitor for double-free or heap corruption signals in applications calling this function. ↗
- ·The exploit PoC hardcodes a private LAN IP (192.168.92.187) as the reverse shell callback target; this is a lab/test address and will differ in real-world attacks. ↗
- ·Reliable exploitation requires ASLR to be disabled; exploitation against hardened systems with ASLR enabled is significantly less reliable. ↗
- ·The exploit title states 'Mbed TLS 3.6.4 - Use-After-Free' but the CVE and NVD description state the vulnerability affects versions *before* 3.6.4; 3.6.4 is the fixed version. ↗
- ·MicroPython is not affected by this CVE despite using Mbed TLS, because it does not call the vulnerable function mbedtls_x509_string_to_names(). ↗
CVSS provenance
nvdv3.19.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
osv9.8CRITICAL
vendor_ubuntu9.8CRITICAL
vendor_debian8.9HIGH
CVEs like this are exactly what “Exploited This Week” covers.
Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.
OSV
mbedtls vulnerabilities
osv·2026-03-25·CVSS 9.8
CVE-2021-44732 [CRITICAL] mbedtls vulnerabilities
mbedtls vulnerabilities
It was discovered that Mbed TLS incorrectly handled memory allocation
failures. A remote attacker could possibly use this issue to crash
the program. This issue only affected Ubuntu 18.04 LTS and Ubuntu
20.04 LTS. (CVE-2021-44732)
Jonathan Winzig discovered that Mbed TLS incorrectly handled crafted
inputs. A remote attacker could possibly use this issue to crash the
program, resulting in a denial of service. This issue only affected
Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS. (CVE-2024-23775)
It was discovered that Mbed TLS incorrectly handled the TLS
handshake. A remote attacker could possibly use this issue to
break the security guarantees of the TLS handshake.
(CVE-2025-27810)
Linh Le and Ngan Nguyen discovered that Mbed TLS incorrectly
documented t
OSV
CVE-2025-47917: Mbed TLS before 3
osv·2025-07-20·CVSS 9.8
CVE-2025-47917 [CRITICAL] CVE-2025-47917: Mbed TLS before 3
Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function mbedtls_x509_string_to_names() takes a head argument that is documented as an output argument. The documentation does not suggest that the function will free that pointer; however, the function does call mbedtls_asn1_free_named_data_list() on that argument, which performs a deep free(). As a result, application code that uses this function (relying only on documented behavior) is likely to still hold pointers to the memory blocks that were freed, resulting in a high risk of use-after-free or double-free. In particular, the two sample programs x509/cert_write and x509/cert_req are affected (use-after-free if the san string contains more th
GHSA
GHSA-7xcg-xp2h-m42v: Mbed TLS before 3
ghsa_unreviewed·2025-07-20
CVE-2025-47917 [HIGH] CWE-416 GHSA-7xcg-xp2h-m42v: Mbed TLS before 3
Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function mbedtls_x509_string_to_names() takes a head argument that is documented as an output argument. The documentation does not suggest that the function will free that pointer; however, the function does call mbedtls_asn1_free_named_data_list() on that argument, which performs a deep free(). As a result, application code that uses this function (relying only on documented behavior) is likely to still hold pointers to the memory blocks that were freed, resulting in a high risk of use-after-free or double-free. In particular, the two sample programs x509/cert_write and x509/cert_req are affected (use-after-free if the san string contains more th
Ubuntu
Mbed TLS vulnerabilities
vendor_ubuntu·2026-03-25·CVSS 9.8
CVE-2025-27810 [CRITICAL] Mbed TLS vulnerabilities
Title: Mbed TLS vulnerabilities
Summary: Several security issues were fixed in mbedtls.
It was discovered that Mbed TLS incorrectly handled memory allocation
failures. A remote attacker could possibly use this issue to crash
the program. This issue only affected Ubuntu 18.04 LTS and Ubuntu
20.04 LTS. (CVE-2021-44732)
Jonathan Winzig discovered that Mbed TLS incorrectly handled crafted
inputs. A remote attacker could possibly use this issue to crash the
program, resulting in a denial of service. This issue only affected
Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS. (CVE-2024-23775)
It was discovered that Mbed TLS incorrectly handled the TLS
handshake. A remote attacker could possibly use this issue to
break the security guarantees of the TLS handshake.
(CVE-2025-27810)
Linh Le
Debian
CVE-2025-47917: mbedtls - Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applicati...
vendor_debian·2025·CVSS 8.9
CVE-2025-47917 [HIGH] CVE-2025-47917: mbedtls - Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applicati...
Mbed TLS before 3.6.4 allows a use-after-free in certain situations of applications that are developed in accordance with the documentation. The function mbedtls_x509_string_to_names() takes a head argument that is documented as an output argument. The documentation does not suggest that the function will free that pointer; however, the function does call mbedtls_asn1_free_named_data_list() on that argument, which performs a deep free(). As a result, application code that uses this function (relying only on documented behavior) is likely to still hold pointers to the memory blocks that were freed, resulting in a high risk of use-after-free or double-free. In particular, the two sample programs x509/cert_write and x509/cert_req are affected (use-after-free if the san string contains more th
No detection rules found.
https://github.com/Mbed-TLS/mbedtls-docs/blob/main/security-advisories/mbedtls-security-advisory-2025-06-7.mdhttps://mbed-tls.readthedocs.io/en/latest/tech-updates/security-advisories/https://lists.debian.org/debian-lts-announce/2025/08/msg00013.htmlhttps://lists.debian.org/debian-lts-announce/2025/08/msg00025.html
2025-07-20
Published