Out-of-bounds read in HTTP client no_proxy handling
Issue summary: An application using the OpenSSL HTTP client API functions may trigger an out-of-bounds read if the 'no_proxy' environment variable is set and the host portion of the authority component of the HTTP URL is an IPv6 address. Impact summary: An out-of-bounds read can trigger a crash which leads to Denial of Service for an application. The OpenSSL HTTP client API functions can be used directly by applications but they are also used by the OCSP client functions and CMP (Certificate Management Protocol) client implementation in OpenSSL. However the URLs used by these implementations are unlikely to be controlled by an attacker. In this vulnerable code the out of bounds read can only trigger a crash. Furthermore the vulnerability requires an attacker-controlled URL to be passed from an application to the OpenSSL function and the user has to have a 'no_proxy' environment variable set. For the aforementioned reasons the issue was assessed as Low severity. The vulnerable code was introduced in the following patch releases: 3.0.16, 3.1.8, 3.2.4, 3.3.3, 3.4.0 and 3.5.0. The FIPS modules in 3.5, 3.4, 3.3, 3.2, 3.1 and 3.0 are not affected by this issue, as the HTTP client implementation is outside the OpenSSL FIPS module boundary.
- Published
- Sep 30, 2025
- Updated
- Jul 14, 2026
- EPSS
- 2.0% · 80th percentile
- CWE
- CWE-125
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Report tools
Action score
24
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 2.0%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Affected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (openssl). Independent of NVD's CPE analysis and usually ahead of it.
OpenSSL OpenSSL
- 3.5.0 and later · before 3.5.4affected · semver
- 3.4.0 and later · before 3.4.3affected · semver
- 3.3.3 and later · before 3.3.5affected · semver
- 3.2.4 and later · before 3.2.6affected · semver
- 3.0.16 and later · before 3.0.18affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Alpine:v3.17 | openssl | before 3.0.19-r0 | 3.0.19-r0 |
| Alpine:v3.19 | openssl | before 3.1.8-r1 | 3.1.8-r1 |
| Alpine:v3.20 | openssl | before 3.3.5-r0 | 3.3.5-r0 |
| Alpine:v3.22 | openssl | before 3.5.4-r0 | 3.5.4-r0 |
| Debian:12 | openssl | before 3.0.17-1~deb12u3 | 3.0.17-1~deb12u3 |
| Debian:13 | openssl | before 3.5.1-1+deb13u1 | 3.5.1-1+deb13u1 |
| Debian:14 | openssl | before 3.5.4-1 | 3.5.4-1 |
| openSUSE:Leap 16.0 | openssl-3 | before 3.5.0-160000.4.1 | 3.5.0-160000.4.1 |
| openSUSE:Tumbleweed | openssl-3 | before 3.5.3-2.1 | 3.5.3-2.1 |
| openSUSE:Tumbleweed | regclient | before 0.10.0-1.1 | 0.10.0-1.1 |
| Red Hat:hummingbird:1 | openssl | before 0:3.5.6-0.1.hum1 | 0:3.5.6-0.1.hum1 |
| SUSE:Linux Enterprise Server 16.0 | openssl-3 | before 3.5.0-160000.4.1 | 3.5.0-160000.4.1 |
Same product
openssl: all recordsOther highest-scoring records for the same primary product.
- CVE-2014-0160The (1) TLS and (2) DTLS implementations in OpenSSL 1.0.1 before 1.0.1g do not properly handle Heartbeat Extension packets, which allows remKEV90Now
- CVE-2021-3711SM2 Decryption Buffer Overflow65This week
- CVE-2003-0545Double free vulnerability in OpenSSL 0.9.7 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code 65This week
- CVE-2016-2108The ASN.1 implementation in OpenSSL before 1.0.1o and 1.0.2 before 1.0.2c allows remote attackers to execute arbitrary code or cause a denia62This week
- CVE-2016-6309statem/statem.c in OpenSSL 1.1.0a does not consider memory-block movement after a realloc call, which allows remote attackers to cause a den60This week
- CVE-2022-3786X.509 Email Address Variable Length Buffer Overflow58Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| OpenSSL OpenSSL | 3.0.18 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.2.6 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.3.5 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.4.3 | Vendor (CNA) |
| OpenSSL OpenSSL | 3.5.4 | Vendor (CNA) |
| alpine:openssl | 3.0.19-r0 · Alpine:v3.17 | Package registry (OSV) |
| debian:openssl | 3.0.17-1~deb12u3 · Debian:12 | Package registry (OSV) |
| opensuse:openssl-3 | 3.5.0-160000.4.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:regclient | 0.10.0-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:openssl | 0:3.5.6-0.1.hum1 · Red Hat:hummingbird:1 | Package registry (OSV) |
| suse:openssl-3 | 3.5.0-160000.4.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Stanislav Fort (Aisle Research)reporter
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2024-5535460 days apartSSL_select_next_proto buffer overread38Monitor
- CVE-2026-84782364 days apartDTLS Retransmits Handshake Messages From a Stale Buffer Offset32Monitor
- CVE-2025-92300 days apartOut-of-bounds read & write in RFC 3211 KEK Unwrap30Monitor
- CVE-2026-28386189 days apartOut-of-bounds Read in AES-CFB-128 on X86-64 with AVX-512 Support30Monitor
- CVE-2026-34180252 days apartHeap Buffer Over-read in ASN.1 Content Parsing30Monitor
- CVE-2026-9076252 days apartOut-of-Bounds Read in CMS Password-Based Decryption30Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-125 · Out-of-bounds ReadCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- github.com/openssl/openssl/commit/2b4ec20e47959170422922eaff25346d362dcb35
- github.com/openssl/openssl/commit/654dc11d23468a74fc8ea4672b702dd3feb7be4b
- github.com/openssl/openssl/commit/7cf21a30513c9e43c4bc3836c237cf086e194af3
- github.com/openssl/openssl/commit/89e790ac431125a4849992858490bed6b225eadf
- github.com/openssl/openssl/commit/bbf38c034cdabd0a13330abcc4855c866f53d2e0
- openssl-library.org/news/secadv/20250930.txt
- www.openwall.com/lists/oss-security/2025/09/30/5
- cert-portal.siemens.com/productcert/html/ssa-032379.html
- cert-portal.siemens.com/productcert/html/ssa-082556.html
- cert-portal.siemens.com/productcert/html/ssa-089022.html
- cert-portal.siemens.com/productcert/html/ssa-253495.html
- cert-portal.siemens.com/productcert/html/ssa-485750.html
- cert-portal.siemens.com/productcert/html/ssa-585531.html
Vendor advisories and official records. Exploit/PoC links are deliberately left out.