# CVE-2021-25636: Incorrect trust validation of signature with ambiguous KeyInfo children > Attackers can bypass digital signature validation in LibreOffice by manipulating XML streams, causing the application to report invalid signatures as valid. - **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 22 Feb 2022 - **Updated:** 3 Aug 2024 - **Also known as:** ALSA-2022:7461, DEBIAN-CVE-2021-25636, GHSA-3cgr-wxhv-h7xw, RHSA-2022:7461, RLSA-2022:7461, SUSE-SU-2022:0886-1, SUSE-SU-2022:1093-1, UBUNTU-CVE-2021-25636, USN-5330-1, openSUSE-SU-2022:0886-1 ## What is CVE-2021-25636? CVE-2021-25636 is a high-severity vulnerability in Fedoraproject Fedora, published on 22 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description LibreOffice supports digital signatures of ODF documents and macros within documents, presenting visual aids that no alteration of the document occurred since the last signing and that the signature is valid. An Improper Certificate Validation vulnerability in LibreOffice allowed an attacker to create a digitally signed ODF document, by manipulating the documentsignatures.xml or macrosignatures.xml stream within the document to contain both "X509Data" and "KeyValue" children of the "KeyInfo" tag, which when opened caused LibreOffice to verify using the "KeyValue" but to report verification with the unrelated "X509Data" value. This issue affects: The Document Foundation LibreOffice 7.2 versions prior to 7.2.5. Weakness: CWE-295 (Improper Certificate Validation), CWE-347 (Improper Verification of Cryptographic Signature) ## Which versions are affected by CVE-2021-25636? It affects 2 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `autocorr-af` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-bg` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-ca` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-cs` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-da` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-de` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-en` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-es` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-fa` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-fi` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-fr` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-ga` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-hr` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-hu` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-is` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-it` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-ja` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-ko` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-lb` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-lt` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-mn` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-nl` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-pl` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-pt` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-ro` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-ru` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-sk` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-sl` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-sr` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-sv` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-tr` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-vi` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `autocorr-zh` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-base` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-calc` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-core` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-data` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-draw` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-emailmerge` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | | `libreoffice-filters` | AlmaLinux:8 | All versions | 1:6.4.7.2-11.el8.alma | Products: Fedoraproject Fedora, Libreoffice Libreoffice. ## How do I fix CVE-2021-25636? Upgrade to a fixed version. ## Is CVE-2021-25636 being exploited? There is no known exploitation of CVE-2021-25636 in the wild and no public exploit code. ## Other vulnerabilities in Fedoraproject Fedora - [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild) - [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild) - [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild) - [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild) - [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-25636 and fix it if it is affected. What it is: CVE-2021-25636 is a high-severity vulnerability in Fedoraproject Fedora, published on 22 Feb 2022. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-25636 in the wild and no public exploit code. Affected product: Fedoraproject Fedora. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-25636/ (Markdown: https://insights.sbomify.com/CVE-2021-25636/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-25636 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-25636 - OSV: https://osv.dev/vulnerability/CVE-2021-25636 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-25636/ Summaries are generated and may contain mistakes; the official description above is the record.